SPM-Physics-Formula-List-Form5

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Physics Equation List :Form 5

Wave

Oscillation

f =1 f = frequency (Hz or s-1)
T T = Period (s)

Displacement-Time Graph

• Amplitude, Period and Frequency can be found from a Displacement-Time Graph

Wave v = velocity (ms-1)
f = frequency (Hz or s-1)
v= fλ λ = wavelength
(m)
Displacement-Distance Graph

λ = Wavelength

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Interference ONE-SCHOOL.NET

Summary λ = ax

D

λ = Wavelength
a = Distance between the two wave sources
x = Distance between two successive anti-node lines or node lines
D = Distance from the wave sources to the plane where x is
measured.

Sum of charge Electricity

Q = ne Q = Charge
n = number of charge particles
Current e = charge of 1 particle

I=Q Q = Charge
t I = Current
t = time

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Potential Difference V = potential difference, ONE-SCHOOL.NET
W = energy
V =W Q = charge (V or JC-1)
Q (J)
V = potential difference, (C)
Ohm’s Law and Resistance I = Current
R = Resistance (V or JC-1)
V = IR (A or Cs-1)
(Ω)
Resistance

R = R1 + R2 R = ( 1 + 1 + 1 )−1
R1 R2 R3
Current
Parallel Circuit
Series Circuit

The current flow into a resistor = the current flow The current flow into a parallel circuit is equal to the
inside the resistor = the current flows out from the sum of the current in each branches of the circuit.
resistor

IA = IB = IC

I = I1 + I2

Example

If the resistance of the 2 resistors is the same, current
will be divided equally to both of the resistor.
In a series circuit, the current at any points of the
circuit is the same.

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Potential and Potential Difference Parallel Circuit

Series Circuit

The sum of the potential difference across individual
resistor in between 2 points in a series circuit is equal
to the potential difference across the two point.

V = V1 + V2 The potential difference across all the resistor in a
parallel circuit is the same.

Example V = V1 = V2

Example

Potential Difference and Electromotive Force

If we assume that there is no internal resistance in the cell, the potential difference across the cell is equal to
the e.m.f. of the cell.

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Electromotive Force and Internal Resistance

E = I (R + r) or E = V + Ir

E = Electromotive Force (V)
r = internal resistance
V = potential difference, (Ω)
I = Current (V or JC-1)
R = Resistance (A or Cs-1)

(Ω)

2 methods to find the internal resistance and electromotive force

a. Open Circuit – Close Circuit method

Open Circuit Close Circuit

In open circuit ( when the switch is off), the In close circuit ( when the switch is on), the

voltmeter shows the reading of the e.m.f. voltmeter shows the reading of the potential

difference across the cell.

• With the presence of internal resistance, the potential difference across the cell is always

less than the e.m.f..

b. Linear Graph method

From the equation,

E = V + Ir
Therefore

V = -rI + E

Gradient od the grapf, m
= -internal resistance

Y intercept of the graph, c
= electromotive force

Electrical Energy E = Electrical Energy (J)
Q = charge
E = QV V = potential difference (C)
(V or JC-1)

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Electrical Power

P=W P = IV P = I2R P = V2
t R
(W or Js-1)
P = Power (J)
W = Work done/Energy change (s)
t = Time (A)
I = Current (V)
V = Potential difference (Ω)

R = Resistance

Efficiency

Electrical efficiency = output power ×100%
input power

Electromagnetism

Root mean Square Value

Vrms = Vp
2

Vrms = root mean square voltage (V)
Vp = peak voltage (V)

Irms = Ip (A)
2 (A)

Irms = root mean square current
Ip = peak current

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Transformer

Input And Output Of A Transformer

Vs = Ns Vp = input (primary) potential difference (V)
Vp N p Vs = output (secondary) potential difference (V)
Np = number of turns in primary coil
Ns = number of turns in secondary coil

Power In A Transformer

Ideal Transformer Vp = input (primary) potential difference (V)
Vs = output (secondary) potential difference (V)
Vp × I p = Vs × I s Ip = input (primary) current (A)
Is = output (secondary) current (A)
Non-ideal transformer

Efficiency = Vs I s ×100%
VpI p

Power Transmission

2Steps to find the energy/power loss in the cable

a. Find the current in the cable by the equation P=IV
b. Find the Power lost in the cable by the equation P=I2R.

Electronic

Energy change of electron in an electron gun

Kinetic energy electrical potential
=

gain energy

1 mv2 = eV v = speed of electron (ms-1)
2 V = potential difference across the electron gun (V)
v = 2eV e = charge of 1 electron (C)
m = mass of 1 electron (kg)
m

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Cathode Ray Oscilloscope ONE-SCHOOL.NET
Transistor - Potential Divider
Vertical scale = Y-gain control
Horizontal scale = Time base
Period = Time for 1 complete Oscillation

Frequency, f = 1
T

Potential difference across resistor R1

= R1 ×V
R1 + R2

Potential difference across resistor R2

= R2 ×V
R1 + R2

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Radioactivity

Alpha decay A X ⎯⎯→ ZA−−42Y + 24He
Beta decay Z

Gamma emission A X ⎯⎯→ Z +A1Y + 0 e
Z −1

1 n→11p + −10e
0

A X ⎯⎯→ A X +γ
Z Z

A = nucleon number
Z = proton number

Half-life

N = (1)n N0 N = Amount of radioisotope particles after nth half life.
2 N0 = Initial amount of radioisotope particles.
n = number of half life

Nuclear Energy - Einstein Formula

E = mc2 m = mass change (kg)
c = speed of light (m s-1 )
E = energy changed
(J)

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