AKTP 2022 INTENSIVE NOTES SPM PHYSICS KSSM (FORM 4 & FORM 5) By AKTP (2023) by AKTP Not for sale
AKTP 2022 1 INTRODUCTION TO PHYSICS A base quantity is a quantity that cannot be defined in terms of other quantities. The fundamental quantities are length, mass, time, electric current and temperature, number of atom and intensity of light There are 7 fundamental units, i.e., metre(m), kilogram(kg), second(s), ampere(A), kelvin (K), mol(n) and Candela (Cd) Prefix is a multiplying factor used to represent large or small physical quantities, e.g. pico, nano, micro, mili, centi, kilo, mega, giga and tera. A derived quantity is a quantity that is obtained by a combination of basic quantities by means of multiplication, division or both. Measurement is the process of determining the value of a physical quantity values using scientific instrument. 2 FORCE AND MOTION I Linear Motion is the motion of an object in a straight line. Distance is the total length of the path travelled by a moving object. Displacement is distance with direction. A scalar quantity is a physical quantity that has magnitude only. (mass, time, temperature, energy, distance etc) A vector quantity is a physical quantity that has magnitude and direction. (Force, velocity, acceleration, displacement etc) Speed is rate of change of distance. Velocity is the rate of change of displacement. = Average speed is total distance moved divided by total time taken. Average velocity is total displacement divided by total time taken. Acceleration is rate of change of velocity = − Acceleration=0, object at rest or constant velocity, net force =0 Ticker tape Constant Velocity = = 8 8 × 0.02 = 50 Constant acceleration = . . = 10 = . . = 70 t=0.02x4=0.08s = . = 750 = . × = 20 = . × = 120 t= 50x0.02=1s = = 100 Average velocity = 4 + 8 + 12 + 16 + 20 + 24 0.02 × 60 = 70 Motion graph Displacement Time graph Gradient of graph =velocity AB: Constant velocity, 20/10=10ms-1 BC: at rest. v=0 A B C D A B C D by AKTP Not for sale
AKTP 2022 CD: constant velocity but in opposite direction, v=-20/5=- 4ms-1 Total displacement =20+-20=0m Total distance =20+20=40m Average velocity =0/35=0ms-1 Average speed =40/35=1.14ms-1 Velocity- Time graph Gradient= acceleration Area under the graph= displacement JK: acceleration constant, 20/10=10 ms-2 KL: deceleration constant, -10/10= -1 ms-2 LM: acceleration =0, constant velocity PM: constant acceleration but in opposite direction, a= -10/5= -2 ms-2 NO : Constant deceleration but in opposite direction a=10/5=2 ms-2 Total displacement (30s to 45s) = × + × = -25m Total distance 30s to 45s = × + × = 150 Average Velocity (30s to 45s) = = −1.67 Average Speed (30s to 45s) = 15 = 10 Equations of linear motion with uniform acceleration are as follows: = + = + = + 2 Inertia Inertia is the resistance of an object to change of its motion. Inertia is nonphysical quantity. Example: Seat belt is used to prevent the passenger fall forward when the car suddenly stops. Headrest is used to prevent the passenger fall backward when the car suddenly moves forward. Pour ketchup out of the bottle, bottle suddenly stop but ketchup continue to flow. Tighten the hammer head by knocking the handle of the hammer. Smaller tanks in train/lorry to reduce inertia and easy to change direction ABS break : avoid skidding (able to change the direction of the vehicle during breaking) Inertia directly proportional to mass Mass of an object is the quantity of matter in that object. Newton’s First Law of motion/Inertia states, if no external force is acting on an object, it will, if stationary remain stationary, if moving keep moving at a steady speed in a straight line. Momentum Momentum of an object is defined as a product of mass and its velocity. = Law of conservation of momentum states that when total momentum before collision and after collision is remains same, provided there are no external forces acting on the system. (It is applied in elastic collision, inelastic collision and explosion) + = + Elastic collision: after collision, the object moves separately Inelastic collision: after collision, the objects stick together move with common velocity Explosion: After explosion, the objects move in opposite direction. Total momentum of the object =0 momentum forward= momentum backward Application momentum Aircraft/Rocket/Boy jump from a boat to land a) Exhaust gas expel (through small diameter of hole) with high velocity b) Exhaust gas produce greater momentum backward c) It will produce an equal momentum but in opposite direction to the aircraft to move forward d) According to conservation of momentum, total momentum before explosion =after explosion. Total momentum for explosion=0 Bowling a) Bowling ball has greater mass b) Bowling ball has greater momentum c) conservation momentum, the bowling pin will move with greater velocity Force Force is pull or push Newton’s second law of motion states that net force acting on an object is directly proportional to the rate of change momentum of the object in the same direction. = = ( − ) Modification car so that it will able to move faster a) low density material for the car (light) b) powerful P by AKTP Not for sale
AKTP 2022 engine (more thrust) c) tire with tread (better grip on the ground) d) aerodynamic shape (reduce air resistance/drag) e) spoiler (better grip on the ground and reduce drag) f) body of the car has lower height (lower centre of gravity, increase stability) Impulse is also known as change in momentum. Impulse = Ft Impulse=m(v-u) Impulsive force is the force that acts on an object within a very short time such as during a collision. = − To reduce impulsive force, use soft material to increase the time of impact. Application of impulsive force and impulse Heading football/swing golf club/swing tennis racket: follow thru- to increase the time for the force to act on the ball, impulse will increase Air bag/mattress/sponge/bend leg while landing/crumple zone in front of car/ car bumper/soft dashboard – increase the time of impact, reduce impulsive force Pile driver – a) hard material of pile (reduce the time of impact, increase impulsive) b) increase the height of the pile driver (fall down with greater velocity, increase the momentum, increase impulsive force. c) The pile is sharp ( increase the pressure by reduce surface area) Gravity A free fall is situation whereby an object falls under the influence of gravitational attractive force only Gravitational field strength is a region where gravitational force act on one unit of mass. Weight of an object is the gravitational pull acting on it. An object is in equilibrium if the resultant of forces acting on it is zero. The object is stationary or velocity is constant A resultant force is a single force that represents in magnitude and direction two or more forces acting on an object. 3 GRAVITATIONS Newton's Law of universal gravitation states that the force of attraction between two objects is directly proportional to product of their masses and inversely proportional to the square of their distance apart. 2 1 2 r m m F G Gravitational field strength, g is maximum at the surface of the planet Centripetal Force, Fc is the net force on a body moving in a uniform circular motion and always directed towards the Centre of the circular path. = t=tension in rope=centripetal force toward centre v=linear velocity (tangen to the circular) Orbital velocity is the velocity needed to achieve balance gravitational force and centripetal force required by satellite to move in the orbit. = 2 = 4 = Kepler’s 1st Law: All planets move in elliptical orbit, with the sun at one focus (law of Orbit) Kepler’s second law: A line that connects a planet to the sun sweeps out equal areas in equal times (Law of Areas). Kepler’s third law: The Square of the period of any planet is directly proportional to the cube of the orbital radius (Law of Periods). The geostationary satellite has the following characteristics: a. It revolves in the same direction as the Earth. b. It rotates with the same period of rotation as that of the Earth (24 hours). by AKTP Not for sale
AKTP 2022 c. It moves directly above the equator. d. The Centre of a synchronous satellite orbit is at the Centre of the Earth. Escape velocity is defined as the minimum velocity required by a mass, m to escape from gravitational pull of the planet to infinity = 2 Earth is able to maintain its atmosphere because the speed of air molecule is smaller than the escape velocity. (Planet has greater mass will greater gravitational pull, greater escape velocity) 4 HEAT AND ENERGY Temperature (T) is a measure of the degree of hotness. Heat is a form of energy transferred from a hot object to a cold one. Two objects are in thermal equilibrium when the net rate of transfer of heat is zero. Temperature for two object is equal. The thermometric property is the physical property of a substance that changes with temperature example volume of mercury, resistance of electricity. Thermometer use thermal equilibrium to measure temperature. Mercury is used as liquid in thermometer because high boiling point, does not stick to the glass, opaque, expand and contract uniformly The temperature on the Celsius scale is given by the formula: = − − × 100 Sensitivity of thermometer can be increased by narrow capillary tube, thin wall glass bulb( heat easy to transfer to the mercury) and smaller scale division Heat that is absorbed or released by an object is = Heat capacity, C of a substance is the quantity of heat required to raise temperature of substance for 1o C = Specific heat capacity, c of a substance is the quantity of heat required to raise the temperature of 1 kg of the substance by 1o C = . Smaller specific heat capacity means the material is fast to get hot and fast to get cold. Lager specific capacity means the substance is slow to get hot and slow to get cold. The substance can store a lot of energy. If the heat supplied by an electrical heater is Pt, then = to increase temperature of substance Application of Specific heat capacity Cooking pot’s body-low specific heat capacity material (fast to get hot), dark colour (absorb more heat), high melting point (not easy to melt), low density material (light), heat conductor (conduct/transfer more heat) Handle cooking pot – high specific heat capacity (slow to get hot), heat insulator (not easy to transfer heat), high melting point (not easy to melt) Container keep food warm - high Specific heat capacity material (slow to get cold), heat insulator material (not conduct heat to surrounding), wrap with insulator, insulator lid, shiny surface inner wall (reflect heat back to the food), layer with vacuum in between (not heat loss because of convection) Car radiator- big fan (more air flow), water as coolant (high specific heat capacity, slow to get hot), more fin (more surface area to release heat), fin made with low specific heat capacity material (fast to get cold), fin with high melting point Sea breeze- Day time, water high specific heat capacity, water slow to get hot, air above land is hot and rise up. Hot air blow from sea to land Land Breeze – night time, water high specific heat capacity, water fast to get hot, hot air above sea rise up. Air blow from land to sea Pressure cooker- strong material (not easy to break), high melting point material (not easy to melt), low specific heat capacity (fast to get hot), valve (release steam to prevent exceed pressure), clamp (prevent lid from opening, to maintain high pressure) Cooling a house: a) more window (more air in and out) b) big window (more air in and out) c) wall and roof with high specific heat capacity (slow to get hot) d) wall with bright colour reflect heat e) install air con (hot air in the house will lose heat) Thermos flask : a) silver inner wall ( reflect heat) b) inner wall two layer in between is vacuum ( prevent heat loss through convention) c) cork made of heat insulator ( prevent heat loss through conduction) d) low density material for the flask e) high specific heat capacity material for flask (slow to get cold) f) wrap the flask with insulator (prevent heat loss to the surronding Latent Heat Latent heat is the quantity of heat absorbed or released when the state of matter changes at constant temperature. = by AKTP Not for sale
AKTP 2022 If the heat supplied by an electrical heater is Pt, then = to change phase of the substane Specific latent heat of fusion of a substance is the quantity of heat required to change 1 kg of the substance from a solid state to a liquid state without change in temperature. Specific latent heat of vaporization of a substance is the quantity of heat required to change 1 kg of the substance from a liquid state to a vapour state without change in temperature. = AB: heat absorb = mcθ, convert to kinetic energy of particle (increase), temperature increase BC: latent absorb = ml, kinetic energy of particle no change, temperature no change. Latent heat of fusion is used to overcome the attractive force between the particle CD: heat absorb = mcθ, convert to kinetic energy of particle (increase), temperature increase DE: latent absorb = ml, kinetic energy of particle no change, temperature no change. Latent heat of vaporisation is used to overcome the attractive force between the particle Application of specific latent heat Steaming food- steam condensate become liquid, release latent heat of vaporisation, food absorb latent heat and get hot. Refrigerator – expansion valve let the freon liquid evaporate become gas and absorb latent heat of vaporisation from the surrounding. Air surrounding loss heat. The gas flow in metal tube (low specific heat capacity) contact with air and cool down the air surrounding. The gas then will be compressed by condenser back to liquid and release latent heat of vaporisation. The freon liquid cool down by fin and flow back to the expansion and the process is repeated. Lemon tea cool down by adding ice. a) ice melt, temperature remain constant b) ice absorb latent heat from lemon tea c) lemon tea loss heat d) temperature lemon tea decrease Hot coffee cools down to room temperature a) coffee high temperature b) coffee loss heat to the air surrounding c) coffee decrease temperature until same temperature e) no net heat transfer f) thermal equilibrium is achieved Cooling effect from sweating. a) sweat evaporate. b) sweat absorb latent heat from the body c) body loss heat d) temperature of body decrease Evaporation is the conversion of liquid to vapour that occurs at the surface of the liquid at any temperature. Evaporation increases if: temperature increase, air blow, temperature surrounding is high, low humidity, low atmospheric pressure. Boiling is the conversion of liquid to vapour at the boiling point. Lower atmospheric pressure will reduce boiling point Gas’s Law Absolute temperature means temperature in unit Kelvin. Absolute zero mean temperature is zero Kelvin where the gas pressure and volume of gas is equal zero. The kinetic energy of the molecule gas is minimum. Boyle’s Law states that for a given mass of gas, the pressure of the gas is inversely proportional to its volume if the temperature is constant. = Air bubble rise up from the bottom of sea, volume increase, water pressure reduces. Pressure and volume of gas is inversely proportional. Depth of water and pressure is directly proportional Charles Law states that for a given mass of gas, the volume of the gas is directly proportional to its absolute temperature if the gas pressure is constant. = When hot air balloon is heat, air molecules move faster, more collision between gas molecules and wall of container, pressure increase. Volume of gas is allowed to expand so that the pressure will be reduced back to original value. Higher volume of hot air balloon, higher buoyant force. Gay Lussa’s Law states that for a given mass of gas, the pressure is directly proportional to its absolute temperature if the volume of the gas is constant. = by AKTP Not for sale
AKTP 2022 Tyre of car after travelling for certain period time, pressure increase when temperature increase. Higher temperature, gas molecules move faster, more collision to the wall of container, more impulsive force, more pressure At the top of the mountain, temperature is lower because atmospheric pressure is lower, temperature decrease 6 LIGHT AND VISION The reflection of light by a plane or curved mirror obeys the Laws of Reflection. The angle of incidence is equal to the angle of reflection. Virtual Images: images that cannot form on the screen. It is not form by the intersection of real ray. It always forms behind mirror Real Image: images that can form on the screen. It is form by the intersection of real ray. Plane mirrors produce images, which are of the same size as the object, virtual and laterally inverted. The image distance is equal to the object distance. Convex mirrors produce images, which are always virtual, upright and diminished (reduced in size). Use as a rear mirror or anti-theft mirror because Wider View. Concave mirror uses as a) parabolic mirror at the back of the touch light. The bulb is put at the focus point. Light will be reflected to infinity. Concave mirror also uses b) as dental mirror (distance object< f, image form will be virtual, upright and magnify) Refraction of light Refraction of light is said to have occurred when there is a change of direction of a ray of light when it enters another transparent medium with a different density. Snell’s Law states that the ratio of the sine of the angle of incidence, i (in air or vacuum) , to the sine of the angle of refraction, r (in denser medium) is a constant. This ratio is also known as the refractive index, n. = = ℎ ℎ = ℎ ℎ sin sin Example: spoon bend inside the water/the depth of water looks shallow- because the light bend away from normal line when travel from denser medium(water) to less dense medium (air). Eyes assume light travel in straight line. Virtual image is formed above the object Total internal reflection The critical angle, c, is the angle of incidence of light, moving from a denser medium towards a less dense medium where the angle of refraction is equal to 90o . If the less dense medium is air, then the refractive index, n of the denser medium is given by, = 1 Total internal reflection is said to occur when a) light travel from denser medium to less dense medium, and b) the angle of incidence is greater than the critical angle. Application total internal reflection Mirage – Hot air near ground, cold air above the ground. Light travel from denser layer (cold) to less dense (layer), Incident angle > critical angel, total internal reflection happens. Eyes assume light travel in straight line, virtual image is formed on the ground. Diamond – higher refractive index (smaller critical angle), smaller critical angle (more total internal reflection), smooth (more total internal reflection) Optical fiber - Flexible (easy to bend), strong (not easy to break), inner core higher refractive index than outer layer (total internal reflection happen), high purity (more signal able to travel without blocking), bundle of optical fiber (more signal) Working principle binocular a) Two Prism 450 -900 - 450 b) light enter perpendicular into the prism c) incident angle=450 d) incident angle> critical angle e) total internal reflection happen f) total internal reflection happen twice in each prism g) a virtual image is formed\ Medium speed direction Higher density/refractive index decrease Toward normal line Lower density/refractive index increase Away from normal line O I eyes H h H-real depth by AKTP h-apparent depth Not for sale
AKTP 2022 Working principle of periscope, a) use to see an object behind an obstacle b) Two prism 450 -900 -450 c) light enter perpendicular into the prism d) incident angle =450 e) incident angle> critical angle f) total internal reflection happen in each prism. g) virtual, upright and same size image is formed h) no multiple image and brighter image compare to periscope which use mirror Rainbow: 1) light enter water droplet and experience refraction and dispersion. 2) Light ray experience total internal reflection on the surface of the water droplet 3) Light experience refraction and dispersion when moving from water to air 4) Rainbow is seen by the observer Lens Convex lenses/converging lens are thicker in the middle section and converge rays that pass through them. Concave lenses/diverging lens are thinner in the middle section and diverge rays that pass through them. The focal length is the distance from the center of the lens to its focal point. Focal length is positive for convex lens and negative for concave length The power of a lens is the reciprocal of its focal length in meters. The diopter (D), is the unit used to measure the power of a lens. = 1 Thickness of lens increase, focal length decrease, power of lens increase The images formed by a concave lens and convex mirror are always virtual, upright and diminished (reduced in size) whereas the images formed by convex lens and concave mirror depend upon its object distance from the lens or mirror Distanc e Obj Characteristics of image u=∞ Real inverted diminished u>2f Real inverted diminished U=2f Real inverted Same size 2f>u>f Real inverted magnified u=f Virtual (at infinity ) upright magnified u<f Virtual upright magnified u=distance of object, v=distance of image The lens formula and linear magnification are given by: Lens formula, = + v will be positive if the image is real. v will be negative if the image is virtual. Linear magnification, = = ℎ ℎ Application Lenses are used in cameras to form images which are real, inverted and diminished (reduced in size). Modification of camera so that the image will be bigger (still smaller than size of object) a) convex lens with smaller focal length (increase the distance of by AKTP Not for sale
AKTP 2022 image) b) greater diameter of convex lens (brighter image) The astronomical telescope consists of a low power objective lens and a high-power eyepiece lens. (Focal length objective > eyepiece) a) u=infinity, 1st image formed is Real, Inverted, and diminished. The 1st image is formed at the focal point of objective len and also the focal point of the eyepiece b) ui=fe (the 1st image at focal point of eyepiece), the final image form is at infinity. c) Magnification= d) Separation between two lens, d= fo+fe e) Bigger diameter of lens produces brighter image The compound microscope consists of two thick high-power lenses (with very short focal lengths). Eyepiece lens has longer focal length compare to objective lens. a) 2f0<u<f0(object is located between f and 2f of the objective Len), 1st image formed is real, inverted and magnify b) ui<fe (1st image is formed very near to eyepiece) final image formed is virtual, inverted compare to object, magnify c) magnification=m0xme d) distance between two lens, d<fo+fe e) Bigger diameter of lens produces brighter image The magnifying glass also known as a simple microscope consists of a single high power convex Len. Object distance, u is less than its focal length, it forms images which are virtual, upright and magnified (increased in size). 5 WAVES Vibration is period to and fro motion following a fixed path. Molecules of a medium will only vibrate and not move together with the waves. Wave transfer energy and momentum Amplitude is the maximum displacement of an oscillating object from its equilibrium position. Higher amplitude, greater energy of wave Frequency is the number of complete vibrations per second. Period is the time taken for one complete oscillation. = T=period, t=time taken, n=number vibrations Relation between period and frequency is = 1 Wavelength is distance between crest to crest or trough to trough Free vibrations are the vibrations of a system at its natural frequency without external disturbance. Damping/attenuation is caused by dissipative force such as friction or air resistance resulting in loss of energy from the vibrating system in the form of heat. (Frequency and period remain constant) Forced vibrations are the vibrations of a system caused by external alternating forces. Natural frequency is the frequency of an oscillating system without influence of any external force. Resonance is the condition of a vibrating system when the force vibration match the object natural frequency, the object will oscillate with maximum amplitude. Application of resonace Microwave oven use resonance to cook: frequency of the microwave is fit equal the natural frequency of the water molecule. Water molecule vibrate to release heat. Breaking Glass: certain frequency of sound wave equal to natural frequency of the glass, glass vibrate and break. Tv and radio: Tuning the natural frequency of radio or Tv B and D is resonance Length pendulum inversely proportional to by AKTP frequency Not for sale
AKTP 2022 to match the frequency of the signal. Signal able to receive and produce sound Longitudinal waves are waves in which the particles of the medium vibrate in the same direction as the direction of propagation of the waves example sound wave Transverse waves are waves in which the particles of the medium vibrate perpendicularly to the direction of propagation of the waves example light, x ray, gamma ray, ultraviolet, water wave etc. Relation between velocity, frequency and wavelength is v = f Reflection of wave incident angle =reflected angle After reflection, speed, frequency and wavelength remain constant. Direction of wave change Wave from infinity will be reflected to focus point of the parabola reflector and vice versa Parabola disc will reflect the microwave from infinity (satellite) to the receiver which located at focus point of the disc. Refraction Refraction of water wave occurs because of the change in its speed and its direction of propagation when it travels through different depths of the water. During refraction into shallow water, the velocity decrease, wavelength decrease and it bends toward normal line. During refraction into deeper water, the velocity of the wave increase, wavelength increase and it bends away from normal line. Sound wave move faster in high temperature of air Refraction of sound wave During night time: a) Hot air near the ground, cold air away from the ground b) sound travel from cold air to hot air c) Speed of sound increase in the hot air layer, wavelength greater in hot air layer, wavelength smaller in cold air layer d) sound bend toward the ground and travel to further distance Refraction of water wave at cape and bay Wave at the middle of sea is straight, parallel and wavelength is greater, greater speed because greater depth Wave near the sea shore, wave is curve follow the shape shallow region, wavelength decrease and speed decrease At cape: amplitude of wave is higher, energy converge to cape (refracted toward normal line) At bay: amplitude wave is low, energy spread to larger area (water wave refracted away from normal line Resort is built at bay because: water calm, shallow, speed water is smaller, wavelength is smaller and less steep To protect harbor/ resort: a) high retaining wall (water will not overflow into the harbor) b) strong retaining wall (not easy to break) c) retaining wall with rough surface (diffuse reflection of water wave) d) retaining wall thick at the bottom (withstand high water pressure) e) build at bay (water is calm) f) small opening retaining wall (harbor)(obvious diffraction) Diffraction Diffraction of waves is the spreading of the wave when the wave bends after crossing an obstacle. It will decrease the amplitude of the wave (energy is reduced) Diffraction will be obvious if the aperture is small or bigger wavelength is used. > size of gap/size of obstacle Obvious Diffraction Not obvious diffraction After diffraction, speed, wavelength and frequency of wave remain constant Sound easy to diffract compare to light because of greater wavelength Application Modification of parabola disc a) Receiver at focus point (receive signal which is reflected by the disc) by AKTP Not for sale
AKTP 2022 b) Parabola disc at higher location (no obstacle) c) Surface of the parabola disc must hard and smooth (good reflector) d) Bigger diameter of disc (receive more signal) e) Use electromagnetic wave (able to pass through vacuum f) Use high frequency of electromagnetic wave example microwave (more energy) g) Able to rotate 3600 , receive signal from different direction h) Relay station (when the signal is block by obstacle, relay station will boost signal) i) Greater wavelength of electromagnetic wave (easy to diffract) If the modification is radar, the answer is same but instead of receiving signal, radar is to receive and emit signal Hologram in debit card or credit card is produced by diffraction of light and is used as the safety feature Elephant produce sound with lower frequency (infra sound) so that it will able to diffract to larger distance Halo is formed when the cloud blocks the sunlight from the sky and a ring of light surrounding the cloud XRD (x ray diffraction) is used in mineralogy. X ray is pass through the mineral/crystal (mostly from rock which is grinded become powder). Map of pattern of x ray diffraction will help to determine type of mineral Interference Interference of waves is the superposition of waves from two coherent sources. Coherence sources meaning the wave have same frequency and in phase Constructive interference is the superposition of two waves which are in phase to form a resultant wave with maximum amplitude. (Crest+ Crest or Trough+ Trough). A line connects all constructive interference is known as antinode line Destructive interference is the superposition of two waves which are out of phase to form resultant wave with zero amplitude (Crest meet with trough). A line connected destructive inference is known nodal line The principle of superposition states that the resultant displacement of two waves at a certain point is the sum of the displacements of the two waves. Wave length, can be determined from the interference pattern by the formula: x =distance between antinode to antinode or node to node D= distance from source to detector line a= distance between two sources of wave Relation of interference pattern depend on distance of x (state the relation between x and other factor ×= ⋋ Interference of light Young double slit experiment a) Monochromatic light (light with one wavelength) b) Young double slit produce 2 coherence sources of light c) bright fringes -constructive inference, dark fringes- destructive interference d) use to measure wavelength of light When red light is used (⋋is greater), distance between bright fringes is bigger (x is greater) Interference of Sound a) 2 loud speakers connected to 1 audio generator b) Experiment conducted at a wide space (empty space) to prevent reflection of sound) c) loud sound (constructive), weak sound (destructive interference) Application Cockpit of aircraft use destructive inference to reduce noise in the cockpit Ship has bulbous bow to produce destructive interference of water wave so that the water around the ship is calm and cause less water drag Coating on the surface of spectacle(glass) will reflect light cause destructive interference so that it will antiglare Sound wave Sound is a longitudinal wave. It cannot travel through vacuum. D ax by AKTP Not for sale
AKTP 2022 Speed of sound: solid>liquid>gas Category of sound frequency Infrasound <20Hz Audio 20Hz-20kHZ Ultrasound >20kHz The vibrations of the guitar string cause a series of air layers in the vicinity(vibrate) to produce compression region, C (high air pressure) and rarefaction region, R (low air pressure) continuously. Good reflector: smooth and hard surface Good absorber of wave: soft and rough surface A louder sound is having a larger amplitude. Sound with higher pitch will have higher frequency. Application of soundwave: a) Measuring depth of sea: transmitter emit ultrasound, ultrasound reach the base of sea, ultrasound reflected, ultrasound is detected. = 2 v=velocity of sound, t=time taken for sound go to and come back, d= depth b) Dolphin/bat /ultrasounds scanning use reflection of ultrasound wave to detect object. Ultrasound is used because- high frequency (more energy/ not easy to diffract/ easy to reflect/ less noise) c) A good audio system for hall: a) soft surface area for wall (absorb sound) b) rough surface area for wall (absorb reflected sound) c) loudspeaker at higher position (no obstacle) d) distance between 2 loudspeaker is greater (more antinode/ distance between antinode decrease) e) loudspeaker is put front of microphone ( to avoid the sound from loudspeaker reenter the microphone) Electromagnetic wave Electromagnetic wave d) Electromagnetic waves are waves consisting of an electrical field and a magnetic field oscillating perpendicularly to each other. e) It is a transverse wave, travel through vacuum, it travels by speed of light, able polarization, have diffraction, reflection, refraction and inference, v=f⋋ f) Electromagnetic wave spectrum consists of radio waves, microwaves, infrared light, visible light, ultra-violet light, x-rays and gamma rays. (Frequency ascending, wavelength descending) Wave Application Radio Telecommunication Microwave Cooking, radar, communication Infra-red Remote control, night vision Visible light Photosynthesis Ultra violet Identify counterfeit note, kill bacteria X ray Scan luggage, scan bone Gamma ray Sterilization, kill cancer cell, detect crack in metal 9 ELECTRICITY Electric current, I is the rate of flow of electric charge. = Electric field is a region in which any charged body will experience electrical force acting on it. if the charge flow, it will become current Electrical Field Strength Electrical field strength at one point defines as the amount electrical force which act one unit of positive charge which located at that point E=F/q E=electrical field strength, q=quantity of charge, F=electrical force. unit is NC-1 Strength of electrical field between two charged parallel plate E=V/d E=electrical field strength, V=potential different, d=distance between two plat. Unit Vm-1 Experiment electric field 1 The ping pong ball continue to oscillate after deflected to one of the plates. The ping pong ball oscillate because experience electrical C R by AKTP Not for sale
AKTP 2022 force after charged Frequency oscillation can be increased if a) voltage EHT increase (stronger electrical field) b) distance between plate is reduce (stronger electrical field) c) mass of ball smaller (smaller inertia) Nylon thread is replaced with copper wire : Ping pong ball does not move (ball become neutral. Neutral object does not experience force in electrical field) Experiment electrical field II Candle flame spread out two portions. Greater portion toward negative plate, smaller portion toward positive plate. Candle flame contains ion. Ion (charges) experience force in electrical field. + ion is heavier and experience greater force toward negative plate Potential difference between two points is defined as work was done to move a unit charge between two that points. = Ohm’s Law states that the current flowing through a conductor is directly proportional to the potential difference across the conductor, provided that its physical condition and temperature remain constant. ∝ = gradient of graph= resistance Greater gradient, greater resistance Circuit to measure the resistance of a conductor Resistance, R the ratio of the potential difference, V across a conductor to the current, I flowing through it. A l R Factor affect resistance of a conductor o Length increase, resistance increase o Cross sectional Area decrease, resistance increase o Material: nichrome (high resistivity), copper (low resistivity) : ρ = RA/l Resistivity, is the electrical resistance per unit length and per unit of cross-sectional area at a specified temperature. Application of appliance using heat (oven, toaster, iron, bulb, electrical kettle) Heating element: a) material with high resistivity (nichrome), b) coil ( increase the length, increase resistance) c) smaller diameter heating element (higher resistance), d) high melting point (not easy to melt), e) low specific heat capacity (fast to get hot) f) each of the heating element connected in parallel (greater voltage across each heating element) Connecting wire: material with low resistance (high current flow into the appliance Handle of the appliance : heat insulator( does not conduct heat), electrical insulator, high specific heat capacity (slow to get hot) Body of the appliance : low density (light), strong ( not easy to break), high melting point (not easy to melt) Fuse of the appliance : value of fuse a bit higher than the rating(to protect the appliance) Earth wire : exceed current will flow to earth Thermostat : Control current flow by using temperature Rheostat : Control current flow/ Fix the current flow through the circuit. by AKTP Not for sale
AKTP 2022 Rheostat a) connected terminal A and B or B and C b) increase the number turn, increase the length, the resistance of resistance will increase c) slider move to adjust the resistance (current) d) slider must made of good electric conductor (to conduct electricity) In a series circuit, the same current passes through each resistor but the potential difference is different. Effective resistance, R=R1+R2+…. Connect more resistor in series, effective resistance will decrease, total current reduces In a parallel circuit, different currents pass through each resistor but the potential difference is same. Effective Resistance, = + +…… No internal resistance Connect more resistor in parallel, effective resistance reduce, total current increase. Voltage across each resistor remain constant, current flow through each resistor remain constant Electromotive force, (e.m.f.) of an electric source is electric energy supplied when 1 C of charge flows through the sources. EMF is the voltage across the dry cell when the circuit is opened E=V+v E=V+Ir E=IR+Ir=I(R+r) V=Potential difference across device v=Voltage loss in the dry cell r= internal resistance Internal resistance, r of a cell resists the flow of current in the cell. E=V+Ir gradient = -internal resistance, y intercept=emf When current increase, the potential difference across the conductor will decrease. (Larger current flow through the internal resistance of dry cell causing voltage loss in dry cell). Result potential difference across conductor/ bulb become dimmer Dry cells are arranged in parallel is brighter, bcos a) Both have same emf b) effective total internal resistance decrease c) Voltage loss in the dry cell decrease d) Voltage across the bulb increase/ current increase Electric power is the rate at which energy is transferred. Power= E/t, rate of change of energy = = Rating kettle 240V, 3kW: The kettle must be connected to 240V of power supply, it will consume 3000J of energy in 1s Efficiency of electrical appliances = × % by AKTP Not for sale
AKTP 2022 10 ELECTROMANGET Electromagnet produce magnetic field when a current is passed through it. The direction of the magnetic field produced by the current in a straight wire can be determined by the Right-Hand Grip rule. The strength of the magnetic field produced by a solenoid increase if: o The number of turns in the coil per unit distance increase. o The magnitude of the current increase. o soft iron core is used o U shape soft iron core with different pole at the end of the core Right hand grip is used to determine the direction of magnetic field for straight wire. Straight wire produces magnetic field in circular shape Catapult field combing two or more magnetic field to produce a resultant force (unbalance force) Fleming’s Left-Hand Rule is used determine the direction force for motors. An armature experience two opposite direction force is known as a couple. It results a turning effect enable the armature of the motor to rotate Increase speed of rotation of dc motor More magnet/stronger magnet/ reduce the distance between the magnet and the coil (increase the strength of magnet) Increase the current flow (increase the strength of electromagnet) Increase the number of turns for coil (increase the strength of electromagnet Semicircular/concave/curve magnet (produce radial field) Reverse the direction of rotation of the dc motor Reverse the polarity of the magnet or Reverse the direction of current Brushed motor: rotor=coil, stator=magnet, cause a lot spark because of contact with split ring, friction a lot and noise. Brushless motor: rotor=magnet, stator=coil, no spark because no commutator, less friction DC motor- use dc current/battery, one split ring/commutator (reverse the direction of current in the coil after 1st half cycle of rotation cycle, it maintains same direction of rotation for the coil) DC motor – when the coil is in vertical position, there is no current flow in the armature, the armature continues to rotate because of inertia AC motor – two slip rings (armature maintain the same connection to ac power supply), after 1st cycle, the ac power supply will reverse the direction of current in the coil to maintain same rotation for the coil Electromagnet Induction Electromagnetic induction is the production of induced current where there is change in magnetic flux/ cutting of magnetic flux Faraday’s Law states that the magnitude induced current in a conductor is directly proportional to the rate of change of magnetic flux Increase the magnitude induce current by a) stronger magnet/curve magnet b) increase the speed of the relative motion between conductor and magnet c) increase number of turns for the coil. d) coil must cut perpendicular to the magnetic flux e) thick copper wire Lenz’s Law states that an induced current always flows in such a direction that it will oppose the change which is causing it. Fleming’s Right-Hand Rule is used determine direction of current generators. by AKTP Not for sale
AKTP 2022 Modify motor to generator: replace dry cell with bulb Modify ac motor to dc motor: change one split ring into two slip rings Induce current is generated but is not a steady current. a) Coil at horizontal position, coil cut perpendicular to magnetic flux- current generated maximum b) coil at horizontal position, coil cut diagonally to the magnetic flux produce zero current dc generator Ac generator Application electromagnet induction Induction cooker a) There are induction coil wire beneath the cooker b) AC flow in the coil produce changing magnetic field c) Pan (made of ferromagnetism) will cut magnetic flux and produce eddy current in the base of the pan d) it will convert electrical to heat e) Ceramic surface must be poor heat conductor Transformer Transformer is a device to change voltage of an alternating current Working principle of transformer: a) ac flow in the primary coil b) primary coil produce changing magnetic field c) varying magnetic field linkage to the secondary coil d) induced emf is produce in the secondary coil Induced ac is produce in the 2nd coil which have the same frequency with 1st coil Voltage in the coil is directly proportional to the number of turns = Step-Up Transformer is used increase output voltage ( > ) , Step-Down Transformer is used to decrease output voltage ( > ) Ideal transformer: no power loss during the transmission of energy (100% Efficiency), input power=output power = , P=VI Reduce energy loss from transformer by using thick copper wire (reduce resistance of the wire), and laminated core (reduce eddy current in the core), soft iron core (easy to magnetized and demagnetized), winding primary coil on the top of the secondary coil/ reduce the distance between primary coil and secondary coil (reduce leakage of field line/hysteresis loss) Transmission of electrical energy Power Loss during transmission of current power through the cables = Reduce energy loss in the cable: a) thick copper cable b) National Grid network National grid Network: Step up transformer: Increase voltage, reduce current, = ) Power station Step up transformer House Step down transformer Smaller current in the cable, smaller power loss in cable by AKTP Not for sale
AKTP 2022 11 ELECTRONICS Thermionic emission is the emission of electrons from the surface of a heated metal. Cathode rays is a beam of high velocity electrons emitted from a heated metal surface (cathode) in a vacuum tube. Rate of thermionic emission increase a) higher temperature of cathode b) greater surface area of cathode c) Oxide alkaline metal d) material for cathode with high melting point and low specific heat capacity Florescent screen of cathode tube will be brighter if the potential difference (EHT) between cathode and anode is increase Cathode ray will have more kinetic energy convert to light The energy of an electron (eV) converted to kinetic energy in a beam of cathode rays is given by: = 1 2 The properties of cathode rays that can be studied by the Maltese Cross Tube, Deflection Tube and Perrins Tube: Properties of cathode rays (a)Moves in a straight line (b)Has momentum and energy (c) Produces phosphorescence when it strikes a fluorescent material. (d) Negatively charged and deflects towards the positive plate (e) Deflected by a magnetic field and the sign of its charge can be verified using Fleming’s Left Hand Rule. Semiconductor materials are solids that have values of electrical resistance between that of conductors and insulators, such as silicon, germanium, Charge carriers in semiconductors are electrons that are negatively charged and holes that are positively charged. Doping is the addition of a small number of impurities (donor atoms and receptor atoms) into the lattice structure of a pure semiconducting material to increase its electrical conductivity. n-type semiconductors are produced when a small amount of pentavalent material (donor atoms) such as antimony, arsenic and phosphorus is doped into the semiconducting material that has only 4 valence electrons and this results in the excess of electrons when covalent bonds are formed. p-type semiconductors are produced when a small amount of trivalent material (receptor atoms) such as boron, gallium, and indium is doped into the semiconducting material this results in a lack of electrons when covalent bonds are formed. A semiconductor diode is formed by combining p-type and n-type semiconductors. p-n junction is the region at which a p-type and n-type meet. A diode allow current to flow in one direction Forward bias : current flow bcos free electron(in n type) amd positive hole (in p-type) is push across p-n junction. Depletion layer is narrow. Resistance diode decrease Reversed bias : current does not flow bcos free electron(in n type) amd positive hole (in p-type) is pull away from p-n junction. Depletion layer is widen. Resistance diode increase A diode functions as a rectifier (comvert ac to dc) Rectification is the process of converting alternating current (ac) to direct current (dc). A capacitor is used to smoothen the current in a halfwave and full-wave rectification circuit. Half wave reticfication For the 1st half cycle, the diode is forward bias, 2nd half cycle the diode is reverse bias by AKTP Not for sale
AKTP 2022 Without capacitor With capacitor Full wave reticfication 1st half cycle , diode D1 and D3 is forward bias 2nd half cycle, diode D2 and D4 is forward bias Without capacitor With capacitor A transistor has three electrodes. (a) Emitter, E – supplies charge carriers to the collector. (b) Base, B – a thin layer sandwiched in between the emitter and collector to control the flow of charges. (c) Collector, C – receives charge carriers from the emmiter. NPN transistor PNP Transistor A npn transistor is produced when a ptype semiconductor is sandwiched between two n-type semiconductors. A pnp transistor is produced when a ntype semiconductor is sandwiched between two p-type semiconductors. A transistor a semiconductor device can function as an automatic switch and an amplifier. Characteritis of transistor a) if Ib=0, Ic=0 b) when Ib incrase, Ic incrase even higher c) Ib<<<<< Ic d) Ie= Ic+ Ib Automatic light switch Resistanc e LDR Voltage LDR (Base voltage Voltage R Trans istor Day decrease decrease increas e Off Nite Increaes Increase decreas e On Resistance LDR increase when dark Resistro(10kΩ) and LDR is know as pontetial divider (total voltage is 6V) Resistor (1kΩ) to limit base current Bulb is to limit collector current Interchange the position of LDR and R, the circuit will switch on the bulb on daytime For npn transistor to work, base and emitter must be forward bias. (base must connected to positive terminal bcos it is semiconductor P, collector must connected to negative terminal of dry cell bcos it is semiconductor n) Calculate the voltage LDR + × = OR = Bridge rectifier by AKTP Not for sale
AKTP 2022 Automatic Heat Switch Resista nce thermis tor Voltage thermis tor Voltage R (base voltage Tra nsis tor High temperatur e lower lower higher on Low temperatur e higher higher lower off Resistance thermistor increase when temperature is low Relay switch use a small voltage circuit to switch on another high voltage circuit Amplifier a. Microphone convert sound energy to electrical energy b. A small base current flow to produce lager collector current c. Capacitor to filter dc d. The varying collector current to loudspeaker e. Loudspeaker convert electrical energy to sound energy current amplification facotr =Ic Ib 12 RADIOACTIVITY Radioactivity is an unstable nucleus decay to become a more stable nucleus by emitting radiation (such as alpha particles, beta particles and gamma rays) and energy Alpha particle, α is the helium nucleus and consists of 2 protons and 2 neutrons. Helium Nucleus , +2 charge, greater mass, low speed, low penetrating power, higher ionizing power. Daughter particle will have proton number decrease by 2, neutron number decrease by 2, nucleon number decrease by 4 X Y He A Z A Z 4 2 4 2 Beta particle, β is a very fast-moving electron , -1 charge, medium mass, medium speed, medium penetrating power, medium ionizing power. Daughter particle will have proton number increase by 1, neutron number decreased by 1, nucleon number no change X Y e A z A z 0 1 1 Gamma rays, γ are electromagnetic waves with very high frequency. No charge, no mass, high speed, high penetrating power, low ionizing power. Daughter particle will have no change in proton and nucleon number X X A Z A Z by AKTP Not for sale
AKTP 2022 Series of decay Examples of detectors of radiation are: Geiger-Muller tube and Cloud chamber Half-life of a radioisotope is the time taken for the activity to decrease to half its initial value. Exponential decrease graph Mass defect or loss of mass occurs in radioactive decay and nuclear reactions. Einstein’s mass-energy relationship states that mass and energy can change from one form to another, and the relationship is given by: = Nuclear Fission is the splitting of a heavy nucleus into two light nuclei when it is bombarded by a neutron. Nuclear Fission produce energy and harmful radiation such as gamma. Chain reaction is the continuous fission of nuclei and this occurs when the new neutrons produced by a fission splits another nucleus. Critical mass is the minimum mass that is required for a chain reaction. Nuclear Fusion occurs when two lighter nuclei combined together to form a heavier nucleus and energy is released. Heat is used to fuse the isotope Hydrogen to form heavy nucleus and radiation like alpha Harmful effects of radiation to human beings are: (a) Somatic effect – damage to body parts except reproductive organs. (b) Genetic effects – damage to cells in reproductive organs. Nuclear Reactors Uranium rods are the fuel rods or the material for the fission reaction. (Uranium is used because it is a heavy unstable nucleus) Uranium must be in solid form (easy to handle), long half life (no need to change from time to time) Graphite core slows down the fast fission neutrons. Control rods control the rate of the fission reaction by absorbing the exceed neutron The coolant (high specific heat capacity, able to store a lot heat) in the reactors carries heat from the reactor to be used in the production of steam. Lead or concrete shield prevents the radiation from being emitted to the surroundings. Uranium experience nuclear Fission. Mass defect and loss energy as heat. Particles vibrate and move in high-speed produce heat. Heavy water absorbed heat. Hot coolant heats up the water in tank and produce steam. Steam rotate the turbine (convert mechanical energy to electrical energy) Precaution Nuclear reactor plant build in rural area/island (away from people) Nuclear waste is store in lead container. Container of nuclear waste is buried underground or metal mines (copper or lead) will able to block radiation handle the radioactive substance by using force (robotic arm) Wear protective suite with lead lining by AKTP Wear glove and glass Not for sale
AKTP 2022 8 PRESSURES Density is defined as the mass per unit volume of a material. Factors that affect density are temperature, impurities and pressure. Oil floats on water because its density is less than the density of water. On the other hand, a stone sinks in water because its density is higher than that of water. Pressure acting on a surface is defined as the perpendicular force per unit area. Smaller area, greater pressure. Example: nail, pile driver and stud on the shoe (better grip on the ground) Greater area, smaller pressure. Example: wooden plank is put on the soft ground to reduce pressure. Pressure in a liquid is defined as the product of the depth in the liquid, the density of the liquid and the acceleration due to gravity. Measure liquid pressure by different depth Pressure at point A =liquid pressure +atmospheric pressure PA= h + Application of pressure in liquid Water dam has thicker wall at the bottom to withstand high water pressure Intravenous bag must put at high location so that the pressure of liquid in the bag is higher and able to flow to the patient Water tank at high place, it will have high water pressure Submarine is built with stronger material to withstand high water pressure The atmospheric pressure is the pressure that the atmospheric layer exerts on the surface of the Earth. Atmospheric pressure = 1 atm = 760mm Hg. The atmospheric pressure decreases when the height from the surface of the earth increases (cause by lower density of air at the top of the mountain) Lower atmospheric pressure will reduce boiling point because water molecules easy to escape to the air surrounding Barometer mercury: measure atmospheric pressure. Height of the column mercury, h is equal to atmospheric pressure. Mercury is used as liquid in barometer because higher density (atmospheric pressure can support until h=76cmHg compare to water h=10m water) Barometer aneroid/altimeter : use atmospheric pressure to measure altitude Gas pressure Kinetic theory of gas a. A large amount of gas molecules b. All gas molecule moves freely and randomly (no attractive force between them) c. They collide each other and with the wall of container (produce impulsive force and Pressure) d. The speed of molecule increases when temperature is increased e. Volume of gas molecule is too small (negligible), volume of gas depends on volume of container To increase gas pressure in a container: a) increase the mass of the gas b) increase the temperature c) reduce the volume of the gas (container) v m A F P P hg A by AKTP Not for sale
AKTP 2022 Pgas = Patmosfera + h Manometer is used to measure gas pressure Manometer also can be used to measure density of liquid Bourdon gauge is another instrument to measure gas pressure without using any liquid and more compatible. Archimedes Principle Archimedes principle states that when a body is (partially or totally) immersed in a fluid, the upthrust on the body is equal to the weight of the fluid displaced. Weight of water displaced = Upthrust= (v=volume of object immersed or volume of water displaced, ρ=density of liquid, g=gravity) Principle of Floatation states: Object float if: Weight of object=upthrust, net force is zero, at rest Object moving upward if: weight of object< upthrust, net force act upward, object accelerate upward Object sinks if: weight of object >upthrust, net force act downward, object accelerate downward Ship a) Ship is able to float on the water b) Ship is lower density than water c) Volume ship is big but a lot empty space d) bigger volume able to displaced more weight water displace (more buoyant force) d) empty space of ship reduce weight even though the size of ship big e) weight of water displaced =weight of ship. Ship float f) Plimsoll line mark the on ship to ensure the ship is loaded within the safe limit in varies density of water Submarine a) Submarine has ballast tank b) ballast tank empty, submarine float, weight submarine=buoyant force c) ballast tank fill with water, weight of submarine > buoyant force, submarine accelerate downward Hydrometer a device used to measure density of liquid. It will displaced more liquid (sink deeper into the liquid) if the liquid measure is lower density a) big bulb (produce more buoyant force) c) long stem (able to measure a wide range of different density of liquid) d) narrow stem (increase sensitivity) e) made of glass (non corrosive) f) lead shot in the bulb ( so that it will able to float vertically g) smallest division of scale ( more accurate/more sensitive) Hot air balloon Helium gas/ hot air in the balloon has lower density compare to air surrounding. Buoyant force act on the balloon is produced by the air surrounding a) hot air is heated, balloon expand/bigger size of balloon (more buoyant force) b) low density of gas in the balloon ( light) c) More burner (increase temperature of gas in the balloon) d) Low density material for the balloon (light) e) Strong material for the balloon ( not easy to break) f) air proof material for the balloon ( the gas does not leak to the surrounding) When buoyant force > weight of balloon, the balloon accelerate upward. When the balloon continues to move upward, density air surrounding decrease. Buoyant force decrease. When buoyant force= weight of balloon, balloon will float in constant height Cartesian diver a) When the bottle is squeezed, pressure transmitted equally throughout the liquid (pascal principle). b) The by AKTP Not for sale
AKTP 2022 trapped air in cartesian diver become smaller, the water enters the diver, the weight of diver increased (weight of diver increase). The diver is being squeezed by pressure surrounding, the volume of the diver become smaller (buoyant force decrease) . Buoyant force < weight of cartesian diver. The diver sinks downward Ship in river and sea water Ship displaced more water in river water. River water is lower density. Ship displaced bigger volume of river water so that weight of water displace can be equal to the weight of the ship. Ship will be able to float Pascal Principle Liquid cannot be compressed Pascal’s Principle states that in a confined fluid, externally applied pressure is transmitted uniformly in all directions in the liquid. 2 2 A F 1 1 A F Multiplier of force, Force an Area is directly proportional to force. Bigger surface area of piston, bigger force Hydraulic brake a) smaller area of master piston/input piston (smaller input force b) bigger area of slave piston/output piston (greater output force) c) transmission pipe made of strong material (not easy to break) d) oil as liquid in the brake (not easy to evaporate/no corrosive/can bot be compress) e) liquid with high boiling point f) higher spring constant for spring (more energy) Bernoulli principle Bernoulli’s Principle states that at any point in where the velocity of fluid increases, its pressure decreases. On the other hand, when the velocity of the fluid at that point decreases, its pressure increases. Aerofoil is the shape for the wing of an airplane. The air moves faster on the upper part of the aerofoil and produces lower pressure. Difference in pressure produce a lift force. Bunsen Burner a) Gas flow into the Bunsen burner b) Gas flow with high velocity through the nozzle (produce low pressure) c) higher atmospheric pressure push air surrounding through the air hole d) Gas mix air e) complete combustion Spoiler (reverse aerofoil shape) a) Spoiler put behind car b) low velocity air above the spoiler c) higher pressure above the spoiler d) different in pressure produce a force acting downward to car toward the ground e) Car better grip on the ground Perfume Spray a) Elastic bulb (able to return to original shape after force is applied b) big bulb (more air produce) c) narrow tube in the middle of tube (air move faster produce low pressure d) higher atmospheric pressure will push the perfume up to the tube. f) narrow nozzle (spray the perfume with smaller droplet) by AKTP Not for sale
AKTP 2022 Ball moves in curve Air above the ball flow same direction the rotation of the ball. Velocity air above the ball is higher, lower pressure above the ball. Different in pressure produce a net force push it upward Aerodynamic is a shape which enables to reduce air resistance. Kinetic theory of matter. (a) Matter consists of discrete particles known as atoms, molecules or ions. (b) The particles are always in random motion. (c) Attractive force and repulsive force exist between the particles. The attractive force occurs when two particles move further from each other, whereas the repulsive force occurs when the particles are nearer to each other. Elasticity of a material is its ability to return to its original form and size when the force acting on it is removed. Surface tension refers to the force that acts at the surface of a liquid and causes that surface to behave like an elastic skin. Cohesive force is the attractive force between molecules of the same materials. Adhesive force is the attractive force between molecules of different materials. 7. FORCE AND MOTION II Adding Force is adding two or more than two force to form a single force by using parallelogram. a) Net force =F1+F2 b) Force P +Force R + Force Q= 0 Resolving a force is replacing a single force by a pair of perpendicular forces provided that the resultant of the two forces is equivalent to the single force. Situation I (pull or push) by AKTP Not for sale
AKTP 2022 Force acting horizontally F=ma 40cos300 -15=12a a=1.637ms-2 Force acting vertically (net force =0) 40sin30+R=12x9.81 R=97.72N b) sling down a slope Let mass of object =10kg, W=10x9.81=98.1N Force act parallel to slope 98.1sin300 =49.05N F=ma, 49.05=10a, a=4.95ms-2 Normal Reaction force, R R=98.1cos300 =84.957N Solve by using triangle . = , X=49.05N F=ma 49.05=10a a=4.95ms-2 Normal Reaction force, R . = y=98.1sin600, R=y84.957N Situation III (Hanging object) Tsin200 + Tsin200 =5N, T=7.3N = T= =7.3N Pulley a) Acceleration: Tension : W 60 x 0 T T T T W 700 700 5N y by AKTP Not for sale
AKTP 2022 Normal Reaction Force Normal Reaction Force Normal Reaction Force b) Acceleration: Tension c) Acceleration Tension Situation Explanation Lift at rest or moving with constant velocity R is define as apparent weight/ reading of weighing machine/ normal reaction force/tension of rope a=0, F=0 R-mg=0 R=mg Lift moves up at an acceleration of a ms-2 Acceleration exit F0 F=ma Lift accelerate upward, R-mg=ma R=mg+ma Lift moves down with an acceleration of a ms-2 Acceleration exit F0 F=ma Lift accelerate downward, mg-R=ma R=mg-ma Elasticity Ability of an object to return to he original shape or length after the force is removed Hooke’s law states that the extension of an elastic spring is directly proportional to the force acting on it provided that the limit of elasticity is not exceeded. a F = k x a by AKTP Not for sale
AKTP 2022 F = the acting force or the effort, X = extension k = the spring constant Spring constant is defined as force per unit extension of a spring. A soft spring has a smaller k value whereas a stiff spring has a larger k value. K represent the stiffness of a material The strength of a material is the ability of the material to withstand external forces before it breaks or snaps. Rattan is a strong but not rigid material. Concrete is both strong and rigid. Rigidity is the ability of a material to withstand external forces acting on it without changing its size or shape. Glass is a rigid but not a strong material. Factors affecting the rate of extension or stiffness of a spring. a) Type of spring material: a steel spring extending shorter than a copper spring) b) smaller Diameter of spring coil, greater spring constant. c) a thicker wire greater spring constant d) Spring arrangement: parallel, greater spring constant e) shorter spring, greater spring constant Series Parallel In series arrangement same load is applied to each spring i.e W. In parallel arrangement the load is shared equally among the springs . i.e W/2 Energy is defined as the capacity of a system to do work. Elastic Potential Energy is defined as energy obtained by object due to its state (extension or compression) = 1 2 = 1 2 Elastic potential energy= area under the graph Law of Conservation of Energy states that energy cannot be created nor destroyed but changes from one form to another 13. QUANTUM PHYSICS Classical physics Electromagnetic wave (light) is continuous spectrum Frequency electromagnetic wave emitted is directly proportional to temperature of the object that are emitted Object are able to emit electromagnetic radiation in any temperature Problem of classical physics Line spectrum emitted by material for certain temperature Ultraviolet catastrophe, the intensity of the electromagnetic wave emitted by a hot object will decrease when the frequency of wave near ultraviolet range If temperature of object is directly proportional to frequency, frequency of electromagnetic wave will be at infinity, in other word the energy of wave can be at infinity value Modern Physics Electromagnetic wave is in quantum, packet(discrete) of energy Temperature of certain material emitted electromagnet in line spectrum (because the wave is emitted in quanta) The intensity of the radiation is low for the high frequency waves One packet of energy E of the energy for radiation of frequency f is given by E=hf h also known as Planck Constant x F k by AKTP Not for sale
AKTP 2022 = ℎ P=nhf P= power of the wave, n=number of photons emitted in 1s Black body An ideal black body is the one that absorb all the radiation (electrical energy, electromagnetic or heat) of any wavelength that fall on it without reflect or transmitted the radiation At the same time when the body is heated, it emits radiation of all possible wavelength, it is known as black body radiator Perfect absorber and Perfect emitter Tympanic thermometer is used to measure infra-red emitted from of ear hole to determine temperature of our body Photoelectric Effect Photoelectric effect: Release photoelectron when light strike a metal surface 4 characteristics of the photoelectric effect 1. The higher the frequency of the photon of light, the higher the kinetic energy of the photoelectrons emitted from the metal surface. 2. the minimum frequency of light needed for a metal to emit electrons is known as the threshold frequency, fo for that metal. 3. The kinetic energy of photoelectrons does not depend on the intensity of light. An increase in the light intensity does not produce photoelectrons with a higher kinetic energy. 4. Photoelectrons are emitted instantaneously when a metal surface is illuminated by light. The emission of electrons from a metal surface by thermionic emission may take a longer time. Einstein’s photoelectric equation: E = W + Kmax ℎ = ℎ + 1 2 E = photon energy W = Work function (minimum energy to release the electron) Kmax = Maximum kinetic energy = threshold frequency (minimum frequency of light to release electron f= frequency of the light ⋋ = threshold wavelength = ⋋ Gradient of graph=Planck constant Wave Particle Duality Wave exhibit the characteristics of particle Small particle also exbibit the characteristics of wave p=momentum, h=Planck constant, = ℎ Since the value of h is very small, particles of large masses will have de Broglie wavelengths which are too short to be detected (diffraction not obvious and interference pattern is not obvious(x, distance between bright fringes is too short ) Electron with smaller mass will show interference and diffraction clearly Cathode ray will able to show wave properties: 2meV h e=charge of electron, m=mass of electron, V =potential difference across cathode and anode Application by AKTP Not for sale
AKTP 2022 Solar Cells : In daylight, the photoelectric effect of solar cells enables electrical energy to be stored in the battery. At night, the LED lamps will light up with the power from the battery. Light Detector Door (auto gate): The automatic door system uses an infra-red light beam and electrical components, known as photocell as safety features. When the light hits the photocell, electron is released due to photoelectric effect and produces a detectable electrical current. When the beam of light is blocked by a person, the electric current is interrupted and the door is alerted to open. Image Sensor: The image sensor is a main component in high-resolution cameras. This component is used to convert light into electrical signals which can be processed to form digital images. Electron microscope: a) Resolving power of the electron microscope is much higher. b) Electron can be accelerated to a very high kinetic energy giving them a very short wavelength compare than those of visible light. c) Therefore, the diffraction effect of electrons as a wave is much less compare to light d) The electron beam is controlled by electrostatic or magnetic lenses to focus the beam to an image e) image is form on the florescent screen f) Two dimensional or three-dimensional image can be formed by AKTP Not for sale