Electromagnetic Waves

Question 1

What are electromagnetic (EM) waves?

Answer 1

Transverse waves that transfer energy from their source to an absorber.

Question 2

How do different substances interact with EM waves?

Answer 2

They may absorb, transmit, refract, or reflect EM waves in ways that vary with their wavelength.

Question 3

What is the speed of EM waves in a vacuum?

Answer 3

3 × 10^8 m/s.

Question 4

What occurs during refraction of EM waves?

Answer 4

A difference in the velocity of an EM wave in different substances.

Question 5

Which part of the EM spectrum can our eyes detect?

Answer 5

Visible light.

Question 6

List the types of EM waves in order of increasing energy.

Answer 6

• Radio waves
• Microwaves
• Infrared (IR)
• Visible light
• Ultraviolet (UV)
• X-rays
• Gamma rays

Question 7

What happens to a refracted ray when it slows down while crossing a boundary?

Answer 7

It bends towards the normal.

Question 8

What happens to a refracted ray when it speeds up while crossing a boundary?

Answer 8

It bends away from the normal.

Question 9

What is a wave front?

Answer 9

An imaginary line at right angles to the direction the wave is moving.

Question 10

What happens to wave fronts when a wave slows down as it crosses a boundary?

Answer 10

The wave fronts become closer together.

Question 11

What is the relationship between the angle of incidence and the angle of refraction when a wave crosses a boundary?

Answer 11

They are related through the change of speed and direction of the wave.

Question 12

Fill in the blank: EM waves are grouped by their _______ and frequencies.

Answer 12

[wavelengths]

Question 13

True or False: All EM waves travel at different velocities through air.

Answer 13

False.

Question 14

What are electromagnetic (EM) waves?

Answer 14

EM waves are waves that vary in frequency and can be absorbed or produced by changes inside an atom or nucleus.

Question 15

What produces gamma rays?

Answer 15

Gamma rays are produced by changes in the nucleus of an atom.

Question 16

What happens when electrons in an atom move down between energy levels?

Answer 16

They emit EM waves.

Question 17

What are the uses of radio waves?

Answer 17

Radio waves are used for television and radio signals.

Question 18

What are microwaves used for?

Answer 18

Microwaves are used in satellite communications and cooking food.

Question 19

What applications utilize infrared waves?

Answer 19

Infrared waves are used in electrical heaters, cooking food, and infrared cameras.

Question 20

What is the use of visible light?

Answer 20

Visible light is used in fibre optic communications.

Question 21

What are ultraviolet (UV) waves used for?

Answer 21

UV waves are used in energy efficient lights and artificial sun tanning.

Question 22

What is the medical application of X-rays?

Answer 22

X-rays are used for medical imaging and treatments.

Question 23

What are gamma rays used for?

Answer 23

Gamma rays are used for killing cancer cells and harmful bacteria.

Question 24

How are radio waves produced?

Answer 24

Radio waves can be produced by oscillations in an electrical circuit.

Question 25

What happens when radio waves are absorbed by a receiver aerial?

Answer 25

They may create an alternating current with the same frequency as the radio waves.

Question 26

What is a radiation dose measured in?

Answer 26

Radiation dose is measured in sieverts.

Question 27

What are some hazards of EM waves?

Answer 27

Hazardous EM waves can cause damage to the body, including ionising radiation.

Question 28

What allows radio waves to travel long distances?

Answer 28

Radio waves can travel long distances through air.

Question 29

Why can radio waves bend around obstructions?

Answer 29

Longer wavelengths allow them to bend around obstructions.

Question 30

What can infrared waves detect?

Answer 30

Infrared waves can detect hot objects, which can be turned into an image.

Question 31

What is a property of visible light regarding information transfer?

Answer 31

Short wavelength means visible light carries more information.

Question 32

What is a potential effect of ultraviolet (UV) rays on skin?

Answer 32

UV rays can damage skin cells, causing premature aging and increasing skin cancer risk.

Question 33

What is the effect of X-rays on living cells?

Answer 33

High doses of X-rays can kill living cells.

Question 34

Fill in the blank: _______ can penetrate the body and cause internal heating.

Answer 34

X-rays

Question 35

True or False: Gamma rays are a form of non-ionising radiation.

Answer 35

False