Topic 6- Electromagnetic waves

Question 1

What type of spectrum do electromagnetic waves form?

Answer 1

A continuous spectrum

Question 1

Order the types of electromagnetic radiation from lowest to highest frequency

Answer 1

Radio waves
Microwaves
Infrared
Visible Light
Ultraviolet
X-rays
Gamma Rays

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 angel of incidence

Question 5

What types 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
-They 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

Electrical heaters
Cooking food
Infrared cameras

Question 11

Give two practical uses for microwave radiation

Answer 11

Satellite communications
Cooking food

Question 12

Give two practical uses for radio waves

Answer 12

Television transmission
Radio transmission

Question 13

What wave phenomenon is used by lenses to form an image?

Answer 13

Refraction

Question 14

How does a convex lens form an image?

Answer 14

Parallel rays of light are refracted and brought together at a point known as the principal focus

Question 15

What is meant by the focal length of a lens?

Answer 15

The distance from the lens to the principal focus

Question 16

What is the difference between the image produced by a convex and a concave lens?

Answer 16

Convex lenses can produce real or virtual images
Concave lenses can only produce virtual images

Question 17

Why does magnification not have a unit?

Answer 17

It is the ratio between image height and object height
Ratios do not require units

Question 18

What determines the colour of visible light waves?

Answer 18

The wavelength and frequency of the light waves

Question 19

What colour of visible light has the highest frequency?

Answer 19

Blue

Question 20

What colour of visible light has the largest wavelength?

Answer 20

Red

Question 21

What is meant by the term ‘specular reflection’?

Answer 21

Reflection from a smooth surface in a single direction

Question 22

What is meant by the term ‘diffuse reflection’?

Answer 22

Reflection from a rough surface which causes scattering

Question 23

How does a red colour filter work?

Answer 23

A red filter absorbs all wavelengths of light other than those in the red range of the spectrum
This means only red light passes through the filter

Question 24

What determines the colour of an opaque object?

Answer 24

Different objects reflect different wavelengths of light by different amounts
The wavelengths that are most strongly reflected determine the colour

Question 25

What happens to the wavelengths of light that aren’t reflected by an opaque object?

Answer 25

Any wavelengths that aren’t reflected are absorbed by the object

Question 26

What colour does an object appear if all wavelengths are reflected by equal amounts?

Answer 26

White

Question 27

What colour does an object appear if all wavelengths are absorbed?

Answer 27

Black