Waves

Question 1

What is ‘rarefaction’?

Answer 1

An area of reduced pressure.

Question 2

What is a longitudinal wave?

Answer 2

Waves where the oscillations are parallel to the direction of wave travel.

Question 3

Give an example of a longitudinal wave.

Answer 3

E.g: sound waves, seismic P-waves, ultrasound waves

Question 4

What is a way to remember longitudinal waves?

Answer 4

‘P’ sound: longitudinal waves (like seismic P-waves) - thought of as pressure or push waves - particles move parallel to the wave.

Question 5

What are the movements of a longitudinal wave like?

Answer 5

Pushing and pulling a stretched slinky.

Question 6

What is a transverse wave?

Answer 6

A wave where the oscillations are perpendicular to the direction of wave travel.

Question 7

What is an example of a transverse wave?

Answer 7

E.g: a Mexican wave, electromagnetic waves (like light waves, microwaves, radio waves)

Question 8

What are the movements of a transverse wave like?

Answer 8

Moving a rope up and down.

Question 9

What is amplitude?

Answer 9

The maximum displacement of a point fixed on a wave from its undisturbed position.

Question 10

What is frequency?

Answer 10

The number of waves passing a fixed point per second.

Question 11

What is period?

Answer 11

The time taken for one complete wave to pass a fixed point.

Question 12

What is wavelength?

Answer 12

The distance from one point on a wave to the same point on the next wave.

Question 13

What is wave speed?

Answer 13

Distance travelled by each wave per second, and the speed energy is transferred by the wave.

Question 14

What equation relates period and frequency?

Answer 14

Period = 1 ÷ frequency

Question 15

What quantity always stays the same?

Answer 15

Frequency

Question 16

What is absorption?

Answer 16

When the energy of a wave is transferred to the energy stores of the substance it travels into.

Question 17

What is reflection?

Answer 17

When the waves bounce back.

Question 18

What is refraction?

Answer 18

When the waves change speed and direction as they cross the boundary.

Question 19

What is transmission?

Answer 19

When the waves carry on moving once the boundary has been crossed.
They may still be refracted.

Question 20

What is an EM wave?

Answer 20

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

Question 21

What is the speed of all EM waves in a vacuum?

Answer 21

3 x 10^8 m/s

Question 22

When does refraction occur in EM waves?

Answer 22

When there is a change in the wave’s velocity.

Question 23

How do sound waves cause us to hear?

Answer 23

Sound waves cause particle vibrations which ultimately cause the vibration of our ear drums (and other parts)

Question 24

Why are ultrasound waves used for medical and industrial imaging?

Answer 24

1. Ultrasound waves are partially reflected when they meet a boundary between two different media.
2. The time taken for the reflections to reach a detector can be used to determine how far away such a boundary is.

Question 25

What is a way to remember the EM spectrum?

Answer 25

**R**aging **M**artians **I**nvade **V**enus **U**sing **X**-ray **G**uns Radio Micro Infrared Visible light UV X-ray Gamma

Question 26

What sort of radiation is emitted by all (hot) objects?

Answer 26

Infrared

Question 27

What colour is the best absorber and emitter of infrared radiation?

Answer 27

Matte black

Question 28

What colour is the worst absorber and emitter of infrared radiation?

Answer 28

Shiny silver

Question 29

Describe the method for the Leslie cube infrared experiment.

Answer 29

1. Fill cube (has black and shiny silver surface) with hot water. 2. Use infrared detector at various points (at same distance from surface). 3. Record temp. 4. Repeat and calculate mean. 5. Determine which surface is better emitter/absorber.

Question 30

Name a use of radio waves.

Answer 30

Television, radio signals

Question 31

Name a use of micro waves.

Answer 31

Satellite communication, cooking food

Question 32

Name a use of infrared waves.

Answer 32

Cooking food, infrared cameras, electrical heaters

Question 33

Name a use of visible light waves.

Answer 33

Fibre optic communication

Question 34

Name a use of ultraviolet waves.

Answer 34

Tanning, energy-efficient lights

Question 35

Name a use of X-rays or gamma rays.

Answer 35

Medical imaging and treatments

Question 36

What is a hazard of UV radiation?

Answer 36

Damage skin cells, premature aging of skin, **skin** cancer, blindness

Question 37

What is a hazard of Gamma and X-rays?

Answer 37

Damage cells, mutation of genes leading to cancer

Question 38

Why are waves further down the EM spectrum more dangerous?

Answer 38

They are more ionising so can damage cells

Question 39

What type of EM wave has the shortest wavelength?

Answer 39

Gamma

Question 40

What type of EM wave has the longest wavelength?

Answer 40

Radio

Question 41

What type of EM wave has the highest frequency?

Answer 41

Gamma

Question 42

What type of EM wave has the lowest frequency?

Answer 42

Radio

Question 43

What does a wave bend towards when it is refracted?

Answer 43

The normal

Question 44

What type of wave is sound?

Answer 44

Longitudinal

Question 45

Where is amplitude measured from?

Answer 45

Middle to peak of wave

Question 46

Where is wavelength measured from?

Answer 46

A point (usually peak) on one wave to identical point on next wave

Question 47

What type of waves are light waves?

Answer 47

Transverse

Question 48

What type of waves are all EM waves?

Answer 48

Transverse

Question 49

How can seismic waves be used to explain the structure of the Earth?

Answer 49

P-waves can travel through liquids and solids S-waves can only travel through solids The fact that P-waves can travel through the Earth tells us that some of the structure of Earth is liquid.

Question 50

What are ultrasound waves?

Answer 50

Waves with a frequency above 20kHz.

Question 51

What colours are part of the visible light spectrum?

Answer 51

Red, orange, yellow, green, blue, indigo, violet