P15 Electromagnetic waves

Question 1

What type of wave are electromagnetic waves?

Answer 1

Transverse

Question 2

Explain why EM waves are not mechanical waves

Answer 2

Because they can travel through a vacuum

Question 3

What do EM waves transfer from their source to an absorber?

Answer 3

Energy

Question 4

Name the electromagnetic spectrum going from longest wavelength to shortest wavelength

Answer 4

Radio waves
Microwaves
Infrared
Visible light
Ultraviolet
X-rays
Gamma rays

Question 5

What part of the EM spectrum can humans see?

Answer 5

Visible light

Question 6

How can electromagnetic waves be produced?

Answer 6

Changes inside of an atom / atomic nucleus

Question 7

How are gamma rays produced?

Answer 7

Changes in the nucleus of an atom

e.g during radioactive decay

Question 8

How can radio waves be produced?

Answer 8

Oscillations in an electrical circuit

Question 9

How can we detect radio waves?

Answer 9

Waves are absorbed and create an alternating current with the same frequency as the radio wave

Question 10

Uses of radio waves

Answer 10

TV and radio signals

Question 11

Why are radio waves suitable for their use?

Answer 11

Can travel a long distance through air

Longer wavelengths can bend around obstructions to allow detections of signals

Question 12

Uses of microwaves

Answer 12

Satellite communications
Cooking food

Question 13

Why are microwaves suitable for their use?

Answer 13

They can pass through the Earth’s atmosphere to reach satellites

Can penetrate into food and are absorbed by water molecules in food, heating it

Question 14

Hazards of microwaves and radio waves

Answer 14

Can penetrate the body and cause internal heating

Question 15

Uses of infrared waves

Answer 15

Electrical heaters
Cooking food
Infrared cameras

Question 16

Why are infrared waves suitable for their uses?

Answer 16

Can transfer energy quickly to heat rooms and food

Sensors can detect infrared waves and turn them in to images

Question 17

Hazards of infrared waves

Answer 17

Can damage or kill skin cells due to heating

Question 18

Uses of visible light waves

Answer 18

Fibre optic communications

Question 19

Why is visible light suitable for its use?

Answer 19

Short wavelength means that visible light carries more information

Question 20

Hazards of visible light

Answer 20

Can damage the retina

Question 21

Uses of ultraviolet waves

Answer 21

Energy efficient light
SUNBEDS

Question 22

Why are ultraviolet waves suitable for their uses?

Answer 22

Carries more energy that visible light

Question 23

Hazards of ultraviolet waves

Answer 23

Can damage skin cells
Increases risk of skin cancer
Can cause blindness

Question 24

Uses of X-Ray waves and gamma rays

Answer 24

Medical imaging and treatments

Question 25

Why are X-rays and gamma rays suitable for their use?

Answer 25

Can easily pass through flesh but not bone High doses kills living cells such as cancer cells Gamma rays can also kill harmful bacteria

Question 26

Hazards of X-rays and Gamma rays

Answer 26

Form of ionising radiation -can damage or kill cells Causes mutations of genes

Question 27

What is refraction?

Answer 27

Waves change speed and direction as they cross the boundary from one substance to another due to change in velocity

Question 28

What happens to the direction of a refracted EM wave when it slows down as it crosses the boundary from one substance to another?

Answer 28

Bends towards the normal