5.7 Electromagnetic Waves

MODUL PDP SPM PASCA PKP
NEGERI PERAK 2020

PHYSICS Form 4

5.7: Electromagnetic Waves

0

5.7 Electromagnetic Waves

Learning Standard:

Pupils are able to:

• characterise electromagnetic waves.
• state the components of the electromagnetic spectrum according to wavelength

and frequencies.
• communicate to explain about the applications of each component in the

electromagnetic spectrum in daily life.

1

5.7 notE

Electromagnetic Waves
1. Electromagnetic waves are made up of an electric field and a magnetic field that

oscillates perpendicularly to one another.

Electromagnetic waves

2.
are transverse waves

do not need medium for can propagate through
propagation vacuum

Characteristics of
Electromagnetic Waves

Speed in vacuum, show phenomena of reflection,
c = 3.00 × 108 m s–1 refraction, diffraction and
interference

2

3. Electromagnetic spectrum

• It is a series of electromagnetic
waves that are arranged in the
order of frequency and wavelength.

• Radio wave • Gamma ray
• Microwave
Electromagneti • X-ray
c spectrum

• Infrared ray • Ultraviolet ray

• Visible light

4. Seven types of electromagnetic waves form a continuous spectrum known as
electromagnetic spectrum.

Electromagnetic spectrum
The energy carried by electromagnetic waves is directly proportional to its frequency.
This means gamma ray and X-ray carry large amount of energy.

3

Applications for each type of electromagnetic wave in daily life

Type of Application
electromagnetic
• Long distance radio communication
wave • Local radio and TV broadcasting
• Wireless communication (Bluetooth,
Radio wave
λ= 10-1– 105 m Wifi, Zigbee dan Z-wave)
• Millimeter-wave machine to scan body

of passengers at airport

Microwave • International communication through
λ= 10-3 – 10-1 m use of satellite

• Mobile phone framework
• Communication between electronic

devices (Wifi, Bluetooth, Zigbee dan Z-
wave)
• Detection of plane radar dan speed
trap
• Cooking using microwave oven

Infrared ray • For cooking (oven, grill and toaster)
λ = 10-6 – 10-3 m • For night vision (infrared camera and

infrared binoculars)
• Drying paint on car
• Treatment of muscle pain
• Remote control device for television

and DVD player

Visible light • Enable living things to see
λ= 10-7 m • Photography
• Photosynthesis in green plants
• Laser light used in cutting of metal,

measurement of land and sending of
information through optical fibres

Ultraviolet ray • Hardens tooth filling material
λ = 10-9 – 10-7 m • Determines authenticity of currency

notes
• Treatment of jaundice in babies
• Purification of drinking water
• Sterilising surgical instruments and

food
• Insect traps

4

X-ray • Detects fracture or broken bones and
λ= 10-11 – 10-9 m examines internal organs

Gamma ray • Checking of welding connections
λ= 10-14 – 10-10 m • Baggage scanning at airports
• Determines authenticity of paintings

• Killls cancer cells in radiotherapy
• Sterilisation of surgical and medical

equipment in bulk
• Used in food processing industry so

that food can last longer

5

5.7 MIND MAP

6

5.7 FAQ

No Questions and Answers
1Q What is electromagnetic waves and its properties?

A These are waves that consist of vibrating electric and magnetic fields. They
transmit energy through matter or across space. Like other waves,
2Q electromagnetic waves have properties of speed, wavelength, and
A frequency.

3Q What can electromagnetic waves travel through?
A
Electromagnetic waves differ from mechanical waves in that they do not
4Q require a medium to propagate. This means that electromagnetic waves can
A travel not only through air and solid materials, but also through the vacuum
of space.
5Q
A What are the seven electromagnetic waves in order?

6Q The Electromagnetic spectrum is generally divided into seven regions, in
A order of decreasing wavelength and increasing energy and frequency. The
common designations are: radio waves, microwaves, infrared (IR), visible
light, ultraviolet (UV), X-rays and gamma rays.

What are examples of devices that use electromagnetic waves?

Electromagnetic waves are ubiquitous in nature (i.e., light) and used in
modern technology—AM and FM radio, cordless and cellular phones, garage
door openers, wireless networks, radar, microwave ovens, etc.

What waves are used to communicate with satellites?

"Microwaves and radio waves are used to communicate with satellites.
Microwaves pass straight through the atmosphere and are suitable for
communicating with distant satellites, while radio waves are suitable for
communicating with satellites in low orbit.

How do electromagnetic waves affect our lives?

Electromagnetic Radiation is a spectrum that can be anything from Radio
Waves to Gamma Rays. We use visible light to see, radio waves to send
information, microwaves to heat food, infrared for sensors, UV is used in
black lights, X-rays let us see bones, and Gamma Rays used to kill cancer cell.

7

5.7 EXERCISE

SECTION A
1. The following shows the arrangement of electromagnetic waves in order of

increasing frequency.

Radio wave, microwave, P, visible light, Q, X-ray, R

What are P, Q and R? Q [MENGANALISIS]
Ultraviolet ray R
P
A Gamma ray Infrared ray Infrared ray

B Ultraviolet ray Ultraviolet ray Gamma ray

C Infrared ray Gamma ray Gamma ray

D Infrared ray Ultraviolet ray

2 Diagram 2 shows an electromagnetic spectrum.

Infrared Visible light Ultraviolet P Gamma ray

Diagram 2

State one use of P. [MEMAHAMI]
A Cooking
B Satellite transmissions C Radiotherapy

D Telecommunication

8

3 Which statement is true about ultra violet ray? [MENGETAHUI]
A It kills cancerous cells

B It cannot travel in vacuum

C It is a transverse wave

D Its wavelength is shorter than the wavelength of X-ray

4 Which of the following statements is true about electromagnetic waves?
[MEMAHAMI]

A They are longitudinal waves

B They are waves that require a medium to travel

C The velocity of the waves is influenced by the wavelength

D They consist of both magnetic fields and electric fields

5 Which is the correct arrangement of electromagnetic waves in order of increasing
frequency?
[MENGANALISIS]
A Infrared rays, Microwaves, Gamma rays. Ultraviolet rays

B Gamma rays, Ultraviolet rays, Infrared rays, Microwaves

C Microwaves, Infrared rays, Ultraviolet rays, Gamma rays

D Ultraviolet rays, Gamma rays, Microwaves, Infrared rays

9

SECTION B

6 The diagram 6 shows the electromagnetic spectrum

R X-ray Ultraviolet Visible Infrared Microwave Radio wave
light
Diagram Rajah 6

(a) State the electromagnetic wave R. [MENGETAHUI]
…………………………………………………………………………….. [ 1 mark]

(b) Give one reason why microwave is used in satellite communication.
[MEMAHAMI]

………………………………………………………………………………….

[ 1 mark]

(c) A radio station emits radio wave at frequency of 100 MHz.

(i) State the frequency in the unit of Hz.

[MENGETAHUI]

………………………………………………………………………….

[ 1 mark]

ii) Calculate the wavelength of the radio wave. (speed of radio wave is
3 x 108 m s-1)

[MENGAPLIKASI KUANTITATIF]

[ 2 marks]
10

5.7 QR CODE

Title 5.7 Electromagnetic Waves QR CODE
link
Wave https://youtu.be/Vqp7RvhPSMg
(Electromagnetic
Waves)

Electromagnetic https://youtu.be/V3QwdcDah9c
waves

Application of https://youtu.be/CxVwdv76KBQ
electromagnetic
waves

REINFORCEMENT https://drive.google.com/file/d/1t3h6YElNfTL26tsf
TEST eHJPlupXkxaF5a7y/view?usp=sharing

ANSWER https://drive.google.com/file/d/1bL670F7wMZVw6
REINFORCEMENT 2cC8REf8Fy3TgFmt-3x/view?usp=sharing
TEST

11

5.7 ANSWER

SECTION A Answer
C
No C
1 C
2 D
3 C
4
5

SECTION B

6 a) Gamma ray
b) Wavelength is high, easily diffracted

C)(i) 1 × 108 Hz

(ii) v = fλ

λ = 3×108 =3m
1×108

12