6.2 ELECTROMAGNETIC WAVES

Question 1

What type of spectrum do

electromagnetic waves form?

Answer 1

A continuous spectrum.

Question 2

How do the speeds of EM radiation differ

in a vacuum and in air?

Answer 2

Electromagnetic waves all travel at the

same speed in a vacuum and in air.

Question 3

What property of waves in different

mediums causes refraction?

Answer 3

● Velocity
● Wave speed is slower in denser
materials, causing refraction

Question 4

In which direction (relative to the normal)
do waves refract when entering a denser
medium?

Answer 4

● They bend towards the normal
● The angle of refraction is less than the
angle of incidence

Question 5

What type of waves can be produced by

oscillations in an electrical circuit?

Answer 5

Radio waves.

Question 6

How can radio waves create an

alternating current in a circuit?

Answer 6

When radio waves are absorbed, they
can induce oscillations in a circuit with
the same frequency as the waves
themselves.

Question 7

Where do gamma rays originate from?

Answer 7

They originate from changes in the

nuclei of atoms.

Question 8

What health effects can ultraviolet waves

cause?

Answer 8

● They can cause the skin to age
prematurely
● The can increase the risk of
developing skin cancer

Question 9

What health effects can X-rays and

Gamma rays cause?

Answer 9

● They are ionising radiation so can
cause mutations in genes
● They can lead to increased risk of
developing various cancers

Question 10

Give three practical uses for infrared

radiation.

Answer 10

1. Electrical heaters
2. Cooking food
3. Infrared cameras

Question 11

Give two practical uses for microwave

radiation.

Answer 11

1. Satellite communications

2. Cooking food

Question 12

Give two practical uses for radio waves.

Answer 12

1. Television transmission

2. Radio transmission

Question 13

What wave phenomenon is used by

lenses to form an image?

Answer 13

Refraction.