Waves

Question 1

What are the two types of waves?

Answer 1

1. Transverse
2. Longitudinal

Question 2

What is a transverse wave?

Answer 2

A wave for which the oscillations are perpendicular to the direction of energy transfer.

Question 3

What is a longitudinal wave?

Answer 3

A wave for which the oscillations are parallel to the direction of energy transfer

Question 4

Give two examples of transverse waves.

Answer 4

1. Electromagnetic waves
2. Seismic s-waves

Question 5

Give two examples of longitudinal waves

Answer 5

1. Sound waves
2. Seismic p-waves

Question 6

What are the two parts of a longitudinal wave called?

Answer 6

Compressions and rarefractions

Question 7

What is a waves amplitude?

Answer 7

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

Question 8

What is wavelength?

Answer 8

• The distance from a point on a wave to the same position on the adjacent wave
• Most commonly peak to peak or trough to trough

Question 9

What is the frequency of a wave?

Answer 9

The number of waves that pass a given point each second

Question 10

What is the unit used for frequency?

Answer 10

Hertz, Hz

Question 11

What is meant by a frequency of 200 Hz?

Answer 11

200 waves pass a given point each second

Question 12

What is wave speed?

Answer 12

The 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

What word is used to describe when a wave bounces off a surface?

Answer 14

Reflection

Question 15

How do sound waves travel through a solid?

Answer 15

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

Question 16

What is the frequency range of human hearing?

Answer 16

20Hz - 20kHz
(1kHz = 1000Hz)

Question 17

What are ultrasound waves?

Answer 17

Waves which have a frequency higher than the upper limit of human hearing
(20kHz)

Question 18

Give an example use for ultrasound waves?

Answer 18

Medical or industrial imaging

Question 19

What natural event causes seismic waves to be produced? What types are produced?

Answer 19

• Earthquakes
• They produce both P-waves and S-waves

Question 20

State a difference between the mediums that P-waves and S-waves can travel through.

Answer 20

-P-waves travel through both solids and liquids
-S-waves only travel through solids

Question 21

What technique is used to detect objects in deep water and measure water depth?

Answer 21

• 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 22

What type of spectrum do electromagnetic waves form?

Answer 22

A continuous spectrum.

Question 23

Order the types of electromagnetic radiation from lowest to highest frequency.

Answer 23

• radio waves
• microwaves
• infrared
• visible light
• ultraviolet
• x-rays
• gamma rays

Question 24

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

Answer 24

Electromagnetic waves all travel at the same speed in a vacuum and in air

Question 25

What property of waves in different mediums causes refraction?

Answer 25

- velocity - wave speed is slower in denser materials, causing refraction

Question 26

In which direction do waves refract when entering a denser medium?

Answer 26

- they bend towards the normal - the angle of refraction is less than the angle of incidence

Question 27

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

Answer 27

Radio waves

Question 28

How can radio waves create an alternating current in a circuit?

Answer 28

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

Question 29

Where do games rays originate from?

Answer 29

They originate from changes in the nuclei of atoms

Question 30

What health effects can ultraviolet waves cause?

Answer 30

- they can cause the skin to age prematurely - they can increase the risk of developing skin cancer

Question 31

What health effects can x-rays and gamma rays cause?

Answer 31

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

Question 32

Give three practical used for infrared radiation.

Answer 32

1. Electrical heaters 2. Cooking food 3. Infrared cameras

Question 33

Give two practical uses for microwave radiation.

Answer 33

1. Satellite communications 2. Cooking food

Question 34

Give two practical uses for radio waves.

Answer 34

1. Television transmission 2. Radio transmission

Question 35

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

Answer 35

Refraction

Question 36

How does a convex lens form an image?

Answer 36

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

Question 37

What is meant by the focal length of a lens?

Answer 37

The distance from the lens to the principal focus

Question 38

What is the difference between the image produced by a convex and a concave lens?

Answer 38

- convex lenses can produce real or virtual images - concave lenses can only produce virtual images

Question 39

Why does magnification not have a unit?

Answer 39

-it is the ratio between image height and object height -ratios do not require units

Question 40

What determines the colour of visible light waves?

Answer 40

The wavelength and frequency of the light waves

Question 41

What colour of visible light has the highest frequency?

Answer 41

Blue

Question 42

What colour of visible light has the largest wavelength?

Answer 42

Red

Question 43

What is meant by the term ‘specular reflection’?

Answer 43

Reflection from a smooth surface in a single direction

Question 44

What is meant by the term ‘diffuse reflection’?

Answer 44

Reflection from a rough surface which causes scattering

Question 45

How does a red colour filter work?

Answer 45

- a red filter absorbs all wavelengths of light other than those in the red range f the spectrum - this means only red light passes through the filter

Question 46

What determines the colour of an opaque object?

Answer 46

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

Question 47

What happens to the wavelengths of light that aren’t reflected by an opaque object?

Answer 47

Any wavelengths that aren’t reflected are absorbed by the object

Question 48

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

Answer 48

White

Question 49

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

Answer 49

Black

Question 50

What do all bodies emit and absorb?

Answer 50

Infrared radiation

Question 51

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

Answer 51

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

Question 52

What is a perfect black body?

Answer 52

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

Question 53

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

Answer 53

None

Question 54

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

Answer 54

- it is a perfect absorber since it absorbs all radiation incident on it - a perfect absorbing is also a perfect emitter

Question 55

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

Answer 55

The wavelength distribution of any emission is dependent on the objects temperature

Question 56

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

Answer 56

The body is absorbing and emitting radiation at the same rate

Question 57

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

Answer 57

The body is absorbing radiation faster than it is emitting it

Question 58

Give two factors that affect the temperature of the Earth

Answer 58

1. The Earth’s rate of absorption and emission of radiation 2. The amount of reflection of radiation into space