Topic 6 - Waves

Question 1

Two types of waves?

Answer 1

Transverse and Longitudinal

Question 2

What is a transverse wave?

Answer 2

Oscillations are perpendicular to the direction of energy transfer.

Question 3

What is a longitudinal wave?

Answer 3

Oscillations are parallel to direction of energy transfer

Question 4

Examples of Transverse waves

Answer 4

Electromagnetic waves
Seismic S-Waves

Question 5

Examples of longitudinal waves

Answer 5

Sound waves
Seismic P-Waves

Question 6

What are two parts of a longitudinal wave called?

Answer 6

Compressions and rarefactions

Question 7

Amplitude definition

Answer 7

Maximum displacement of a point on a wave from it’s undisturbed position

Question 8

Wavelength definition

Answer 8

Distance from a point on a wave to the same position on the adjacent wave
Peak to peak
Trough to trough

Question 9

Frequency

Answer 9

number of waves that pass a given point each second

Question 10

Unit for frequency

Answer 10

Hz

Question 11

What does a frequency of 200hz mean?

Answer 11

200 waves pass a point each second.

Question 12

Wave Speed definition

Answer 12

Speed at which the wave moves or at which energy is transferred through a medium.

Question 13

What does a wave transfer?

Answer 13

Energy

Question 14

Wave speed equation

Answer 14

Wavespeed = frequency x Wavelength

Question 15

Reflection

Answer 15

When a wave bounces off a surface

Question 16

How do sound waves travel through a solid

Answer 16

particles in the solid vibrate and transfer kinetic energy through the material

Question 17

frequency range of human hearing

Answer 17

20hz - 20khz

Question 18

What are ultrasound waves?

Answer 18

Waves with a higher frequency than human hearing (20khz)

Question 19

Use for ultra sound waves

Answer 19

Medical or industrial imaging

Question 20

What causes seismic waves?

Answer 20

Earthquakes - they produce P and S-waves

Question 21

Difference between the mediums P-waves and S-waves can travel through

Answer 21

P-waves travel through both solids and liquids
S-waves only through solids and not liquids

Question 22

How do you detect objects in deep water and measure the water depth?

Answer 22

Echo sounding
High frequency sound waves are emitted, reflected and detected
Time difference between emission and detection, alongside wave speed, are used to calculate distances

Question 23

What type of spectrum do electromagnetic waves form?

Answer 23

A continuous spectrum

Question 24

Electromagnetic waves from lowest to highest frequency

Answer 24

Radio
Micro
Infrared
Visible
Ultraviolet
X-Rays
Gamma Rays

Question 25

How do the speeds of EM radiation differ in a vacuum and in air?

Answer 25

EM Waves all travel the same speed in a vacuum and in air

Question 26

What property of waves in different mediums causes refraction?

Answer 26

Velocity Wave speed is slower in denser materials, causing refraction

Question 27

In which direction (relative to the normal) do waves refract when entering a denser medium?

Answer 27

They bend towards the normal The angle of refraction is less than the angle of incidence

Question 28

What type of waves can be produced by oscillations in an electrical ciruit?

Answer 28

Radio waves

Question 29

How do radio waves create an AC current in a circuit?

Answer 29

When radio waves are absorbed, they can induce oscillations in a circuit with the same frequency as the waves themselves.

Question 30

Where do gamma rays originate from?

Answer 30

Changes in the nuclei of atoms

Question 31

Health effects of UV waves

Answer 31

Can cause the skin to age prematurely Increases the risk of developing cancer

Question 32

Health effects of X and Gamma Rays

Answer 32

They are ionising radiation so can cause mutations in genes They can lead to increased risk of developing various cancers

Question 33

Three practical uses for infrared radiation

Answer 33

Electrical heaters Cooking food Infrared cameras

Question 34

Two practical uses for microwave radiation

Answer 34

Satellite communications Cooking food

Question 35

Two practical uses for radio waves

Answer 35

Television transmission Radio transmission

Question 36

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

Answer 36

Refraction

Question 37

How does a convex lens form an image?

Answer 37

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

Question 38

Focal length of a lens definition

Answer 38

Distance from the lens to the principal focus

Question 39

Difference between the image produced by a convex and a concave lens

Answer 39

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

Question 40

Why does magnification not have a unit

Answer 40

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

Question 41

What symbol is used to represent a convex lens in a ray diagram

Answer 41

Arrows pointing away from centre of line (outwards)

Question 42

What symbol is used to represent a concave lens in a ray diagram?

Answer 42

Arrows pointing inwards towards the centre of line

Question 43

What determines the colour of visible light waves?

Answer 43

Wavelength and frequency

Question 44

What colour of visible light has the highest frequency?

Answer 44

Blue

Question 45

What colour of visible light has the largest wavelength?

Answer 45

Red

Question 46

Specular reflection

Answer 46

Reflection from a smooth surface in a single direction

Question 47

Diffuse reflection

Answer 47

Reflection from a rough surface which causes scattering

Question 48

How does a red colour filter work?

Answer 48

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 49

What determines the colour of an opaque object?

Answer 49

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

Question 50

What happens to the wavelengths of light that isn't reflected by an opaque object?

Answer 50

They get absorbed

Question 51

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

Answer 51

White

Question 52

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

Answer 52

Black

Question 53

What do all objects emit and absorb?

Answer 53

Infrared radiation

Question 54

What happens to the quantity of infrared radiation emitted by an object as temperature increases?

Answer 54

The hotter the object, the more infrared radiation it will emit.

Question 55

What is a perfect black body?

Answer 55

An object that absorbs all of the radiation that is incident upon it

Question 56

How much radiation does a perfect black body reflect or transmit?

Answer 56

None

Question 57

Why is a perfect black body the best possible emitter of radiation?

Answer 57

It is a perfect absorber since it absorbs all radiation incident on it A perfect absorber is also a perfect emitter

Question 58

Other than the intensity of radiation emitted, how does increasing the temperature of an object affect its emissions?

Answer 58

The wavelength distribution of any emission is dependent on the object's temperature.

Question 59

What can be said about the rates of emission and absorption for a body at constant temperature?

Answer 59

They are the same rate

Question 60

Rates of emission and absorption for a body increasing in temperature

Answer 60

The body is absorbing radiation faster than it is emitting it

Question 61

Factors affecting temperature of the Earth (physics)

Answer 61

Earth's rate of absorption and emission of radiation Amount of reflection of radiation into space