Waves

Question 1

State the two types of waves

Answer 1

Transverse and logitudinal

Question 2

Describe a transverse wave

Answer 2

A wave with oscillations at right angles/perpendicular to the direction of energy transfer

Question 3

Describe a longitudinal wave

Answer 3

A wave with oscillations parallel to the direction of energy transfer

Question 4

Give two examples of transverse waves

Answer 4

EM waves including light, water waves

Question 5

Give one example of a longitudinal wave

Answer 5

Sound

Question 6

Define amplitude

Answer 6

The vertical distance from the middle point to the peak/crest or the trough

Question 7

Define wavelength

Answer 7

The horizontal distance from the peak/crest of one wabe to the peak/creast of the next wave (one full wave)

Question 8

Define displacement

Answer 8

The distance from the lowest point of a wave (trough) to the highest point of a wave (peak/crest)

Question 9

What is a wave’s period?

Answer 9

The time it takes to complete one full wave

Question 10

What is the equation which links wave speed, wavelength and frequency?

Answer 10

V = f x λ

Question 11

Define frequency

Answer 11

How many waves there are per second

Question 12

What are the units for frequency?

Answer 12

Hertz (Hz)

Question 13

State the seven EM waves in order of increasing frequency

Answer 13

Radio waves, micro waves, infrared, visible light, ultra violet, x-rays, gamma rays

Question 14

State the uses of radio waves

Answer 14

TV signals, satellite communications

Question 15

State the uses of micro waves

Answer 15

Cooking food, mobile phone signals

Question 16

State the uses of infrared radiation

Answer 16

Thermal imaging cameras/night vision cameras, cooking and heating

Question 17

State the uses of visible light

Answer 17

Photography

Question 18

State the uses of ultra violet

Answer 18

Tanning beds, detecting forged bank notes (invisible secruity markings), sterilising water

Question 19

State the uses of x-rays

Answer 19

Airport scanners, detecting broken bones

Question 20

State the uses of gamma rays

Answer 20

Treating cancer, sterilising food and medical equipment

Question 21

What is ionising radiation?

Answer 21

Radiation that turns atoms into ions

Question 22

What are the dangers of ionising radiation?

Answer 22

Damage to DNA and cells, mutations, uncontrolled cell growth/tumours, cancer

Question 23

If wave speed is constant, how are frequency and wavelength linked?

Answer 23

They are indirectly propertional - as one increases, the other decreases

Question 24

At what speed do all EM waves travel in a vacuum?

Answer 24

3 x 108 m/s

Question 25

How do you measure wavelength using a ripple tank?

Answer 25

Use a strobe light to form a still image of the waves, measure the length of 10 waves and divide by 10 to get the wavelength of one wave

Question 26

How do you measure frequency using a ripple tank?

Answer 26

Count the number of waves passing a certain point in 30 seconds and divide by 30 to get the number of waves per second

Question 27

How do you calculate wave speed in a ripple tank without wavelength and frequency?

Answer 27

Measure the length of the ripple tank, time how long it takes for one wave to travel from one end to the other and use the equation: v = s/t

Question 28

How do you measure wavelength using waves on a string?

Answer 28

Measure the length of the string and divide it by the number of half waves to get half a wavelength. Multiply by two to get one full wavelength

Question 29

How do you generate a wave on a suspended string?

Answer 29

Using a signal generator with a set frequency

Question 30

Describe diffuse reflection

Answer 30

When light hits a rough surface, the light rays bounce off in different directions

Question 31

Describe specular reflection

Answer 31

When light hits a smooth surface, the light rays bounce off in the same direction to form a mirror image

Question 32

What is the law of reflection?

Answer 32

The angle of incidence is equal to the angle of reflection

Question 33

Describe refraction from air into water or glass

Answer 33

When a wave passes from a less dense medium into a more dense medium, the wave slows down and changes direction

Question 34

Describe refraction from water or glass into air

Answer 34

When a wave passes from a more dense medium into a less dense medium, the wave speeds up and changes direction

Question 35

What is the normal?

Answer 35

A perpendicular line at right angles to a surface

Question 36

On a wave front diagram, how could we show that a wave has slowed down?

Answer 36

The wave fronts would be closer together

Question 37

On a wave front diagram, how could we show that a wave speeds up?

Answer 37

The wave fronts would be further apart

Question 38

Describe diffraction

Answer 38

The bending of a wave around objects or through gaps between objects

Question 39

How will a narrow gap affect a wave?

Answer 39

The wave will curve more

Question 40

How will a wide gap affect a wave?

Answer 40

The wave will curve slightly at the edges

Question 41

Which surfaces are the best absorbers and emitters of infrared radiation?

Answer 41

Black, matt surfaces

Question 42

Which surfaces are the worst absorbers and emitters of infrared radiation?

Answer 42

Light, shiny surfaces

Question 43

Which surfaces are the best reflectors of infrared radiation?

Answer 43

Light, shiny surfaces

Question 44

Which surfaces are the worst reflectors of infrared radiation?

Answer 44

Black, matt surfaces

Question 45

What is the relationship between wave speed, wave frequency and wavelength ?

Answer 45

wave speed = frequency × wavelength

Question 46

What happens to light as it travels from a less dense to a more dense medium?

Answer 46

Slows down and bends towards the normal