6. Waves

Question 1

What do all waves transfer?

Answer 1

Energy from one place to another without transferring matter.

Question 2

What does oscillate mean?

Answer 2

To move or vibrate about a fixed position.

Question 3

What are the two types of waves?

Answer 3

Transverse and longitudinal.

Question 4

In a transverse wave

Answer 4

how are vibrations related to energy transfer?

Question 5

In a longitudinal wave

Answer 5

how are vibrations related to energy transfer?

Question 6

What four quantities describe waves?

Answer 6

Amplitude, wavelength, frequency, and period.

Question 7

What is amplitude?

Answer 7

The maximum displacement of a point from its rest position.

Question 8

What is wavelength?

Answer 8

The distance between the same point on two consecutive waves (e.g. crest to crest).

Question 9

What is frequency?

Answer 9

The number of waves passing a point each second.

Question 10

What are the units of frequency?

Answer 10

Hertz (Hz).

Question 11

What is period?

Answer 11

The time for one complete wave to pass a point.

Question 12

What is the equation linking period and frequency?

Answer 12

T = 1 / f

Question 13

Units for T = 1 / f

Answer 13

T in seconds (s), f in hertz (Hz)

Question 14

What is wave speed?

Answer 14

The distance travelled by a wave per second.

Question 15

What is the equation for wave speed?

Answer 15

v = f λ

Question 16

Units for v = f λ

Answer 16

v in metres per second (m/s), f in hertz (Hz), λ in metres (m)

Question 17

What does wave speed depend on?

Answer 17

The medium the wave travels through.

Question 18

What is a mechanical wave?

Answer 18

A wave that needs a medium to travel through (e.g. sound).

Question 19

What type of waves are electromagnetic waves?

Answer 19

Transverse.

Question 20

Can electromagnetic waves travel through a vacuum?

Answer 20

Yes, all EM waves can travel through a vacuum.

Question 21

What is the order of the electromagnetic spectrum (lowest to highest frequency)?

Answer 21

Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.

Question 22

What happens to wavelength as frequency increases?

Answer 22

It decreases.

Question 23

What happens to energy as frequency increases?

Answer 23

It increases.

Question 24

What part of the EM spectrum can humans detect?

Answer 24

Visible light.

Question 25

What happens to light when it passes from one medium to another?

Answer 25

It may be refracted (change direction).

Question 26

Why does refraction occur?

Answer 26

Because wave speed changes between materials.

Question 27

When light enters a denser medium which way does it bend?

Answer 27

Towards the normal

Question 28

When light enters a less dense medium which way does it bend?

Answer 28

Away from the normal

Question 29

What is the normal line?

Answer 29

An imaginary line at 90° to the surface at the point of incidence.

Question 30

What can happen to a wave at a boundary?

Answer 30

Reflection, refraction, absorption, or transmission.

Question 31

What is reflection?

Answer 31

When a wave bounces off a surface.

Question 32

What is the law of reflection?

Answer 32

Angle of incidence = angle of reflection.

Question 33

What can ray diagrams show?

Answer 33

The behaviour of light rays during reflection or refraction.

Question 34

What is diffraction?

Answer 34

The spreading out of waves as they pass through a gap or around an obstacle.

Question 35

What affects the amount of diffraction?

Answer 35

The size of the gap relative to the wavelength.

Question 36

What happens to sound when it travels through different media?

Answer 36

Speed and wavelength change; frequency stays the same.

Question 37

What is the range of human hearing?

Answer 37

Approximately 20 Hz to 20,000 Hz.

Question 38

How do we hear sound?

Answer 38

Sound waves cause vibrations in the ear drum, which are converted to electrical signals by the brain.

Question 39

Why can sound not travel through a vacuum?

Answer 39

There are no particles to transfer the vibrations.

Question 40

How are ultrasound waves different from normal sound?

Answer 40

Ultrasound has frequencies above 20,000 Hz.

Question 41

What are some uses of ultrasound?

Answer 41

Medical imaging, industrial flaw detection, sonar.

Question 42

How does sonar use sound waves?

Answer 42

Time taken for reflection (echo) used to calculate distance (s = v t / 2).

Question 43

What are seismic waves?

Answer 43

Waves produced by earthquakes that travel through Earth.

Question 44

What are the two types of seismic waves?

Answer 44

P-waves (longitudinal) and S-waves (transverse).

Question 45

What do seismic waves tell us about the Earth’s structure?

Answer 45

Changes in speed and path reveal properties of the Earth's core and mantle.

Question 46

What are radio waves used for?

Answer 46

Broadcasting, communications, Bluetooth.

Question 47

What are microwaves used for?

Answer 47

Satellite communications, cooking food.

Question 48

How do microwaves cook food?

Answer 48

Microwaves are absorbed by water molecules, heating the food.

Question 49

What are infrared waves used for?

Answer 49

Heaters, thermal cameras, remote controls.

Question 50

What is visible light used for?

Answer 50

Cameras, fibre optics, and vision.

Question 51

What are ultraviolet waves used for?

Answer 51

Security marking, fluorescent lamps, sunbeds.

Question 52

What are X-rays used for?

Answer 52

Medical imaging and treatments.

Question 53

What are gamma rays used for?

Answer 53

Sterilising food and medical equipment, treating cancer.

Question 54

What are the dangers of ultraviolet radiation?

Answer 54

Can cause skin damage and increase the risk of skin cancer.

Question 55

Why are X-rays and gamma rays dangerous?

Answer 55

They are ionising and can cause cell damage or mutation leading to cancer.

Question 56

Which EM waves are ionising?

Answer 56

X-rays, and gamma rays.

Question 57

What can change when EM waves are absorbed by atoms?

Answer 57

Electron energy levels (electrons move up or drop down).

Question 58

What happens to EM waves when they meet materials?

Answer 58

They may be absorbed, transmitted, or reflected depending on wavelength.

Question 59

What does the effect of EM waves on materials depend on?

Answer 59

The wave's frequency and the material's properties.

Question 60

How can the effects of ionising radiation be reduced?

Answer 60

Shielding, limiting exposure time, and increasing distance from the source.