Section 3

Question 1

What is wavelength?

Answer 1

The distance from one peak to the next.

Question 2

What is frequency?

Answer 2

How many complete waves there are per second.

Question 3

What is frequency measured in?

Answer 3

Hertz (Hz)

Question 4

What is the amplitude?

Answer 4

Height of the wave from the rest to crest.

Question 5

What is the period?

Answer 5

The time it takes for one complete wave to pass a point.

Question 6

What is the period measured in?

Answer 6

Seconds.

Question 7

Examples of transverse wave?

Answer 7

Light and all other EM waves.

Question 8

Describe transverse waves.

Answer 8

The vibrations are at 90 degrees to the direction energy is transferred by the wave.

Question 9

Example of longitudinal waves?

Answer 9

Sound and ultrasound.

Question 10

Describe a longitudinal wave.

Answer 10

The vibrations are along the same direction as the wave transfers energy.

Question 11

What does reflected mean?

Answer 11

They rebound off the material.

Question 12

What does refracted mean?

Answer 12

They go through the new material but change direction.

Question 13

Which has the lowest frequency: radio waves or gamma rays?

Answer 13

Radio waves.

Question 14

Which has the longest wave length: radio waves or gamma rays?

Answer 14

Radio waves.

Question 15

What 2 things do all EM waves have in common?

Answer 15

They are all transverse and all travel at the same speed through a vacuum.

Question 16

What are radio waves mainly used for?

Answer 16

Communications.

Question 17

Why can long wave radio be transmitted around the world?

Answer 17

Long wavelengths diffract around the curved surface of the earth.

Question 18

Why can short-wave radio signals be received a long distance from the transmitter?

Answer 18

They are reflected from the ionosphere.

Question 19

What are microwaves used for?

Answer 19

Satellite communication.

Question 20

What else are microwaves used for?

Answer 20

Cooking.

Question 21

How do microwaves cook food?

Answer 21

The microwaves are absorbed by the water molecules in the food. They penetrate a few centimetres into the food before being absorbed. The energy is then conducted or connected to other parts of the food.

Question 22

What is infrared radiation used in?

Answer 22

Heating and to monitor temperature.

Question 23

How does night-vision equipment work?

Answer 23

The equipment turns the radiation into an electrical signal, which is displayed on a screen as a picture, allowing things which would otherwise be hidden in the dark to be seen.

Question 24

What is ultraviolet used in?

Answer 24

Fluorescent lamps.

Question 25

What do we use X-Rays for?

Answer 25

They are used to view the internal structures of objects and materials, including our bodies.

Question 26

What is gamma radiation used for?

Answer 26

Sterilising medical equipment and food.

Question 27

What types of radiation are absorbed by the body and cause the heating of cells?

Answer 27

Microwaves.

Question 28

What radiation can cause cancerous changes in living cells?

Answer 28

Gamma rays

Question 29

Why do microwaves need to have shielding?

Answer 29

To prevent microwaves from reaching the user.

Question 30

Why can infrared be dangerous?

Answer 30

Too much exposure can cause skin burns.

Question 31

Why is ultraviolet dangerous?

Answer 31

It damages surface cells and can cause blindness.

Question 32

How is a virtual image formed?

Answer 32

When the light rays bouncing off an object onto a mirror are diverging, so the light from the object appears to be coming from a completely different place.

Question 33

Why does white light disperse into different colours as it enters a prism?

Answer 33

Different wavelengths of light refract by different amounts.

Question 34

When entering a triangular block does the light diffract towards or away from the normal?

Answer 34

Towards.

Question 35

Sinc =

Answer 35

1/n

Question 36

When does total internal reflection occur?

Answer 36

When the angle of incidence is greater than the critical angle.