Waves Flashcards

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1
Q

What are the two types of waves?

A
  1. transverse
  2. longitudinal
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2
Q

What is a transverse wave?

A

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

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3
Q

What is a longitudinal wave?

A

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

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4
Q

Give two examples of transverse waves.

A
  1. electromagnetic waves
  2. seismic s-waves
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5
Q

give two examples of longitudinal waves

A
  1. sound waves
  2. seismic p-waves
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6
Q

What are the two parts of a longitudinal wave called?

A

compressions and rarefactions

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7
Q

what is wave’s amplitude?

A

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

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8
Q

What is wavelength?

A

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

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9
Q

What is the frequency of a wave?

A

The number of waves that pass a given point each second

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10
Q

What is the unit used for frequency?

A

Hertz, Hz

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11
Q

What is meant by a frequency of 200Hz?

A

200 waves pass a given point each second.

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12
Q

What is wave speed?

A

The speed at which the wave moves or at which energy is transferred through a medium

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13
Q

What does a wave transfer?

A

Energy

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14
Q

State the equation used to calculate wave speed. Give appropriate units.

A

Wave speed = Frequency x Wavelength
speed (m/s), Frequency (Hz), Wavelength (m)

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15
Q

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

A

Reflection

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16
Q

How do sound waves travel through a solid?

A

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

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17
Q

What is the frequency range of human hearing?

A

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

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18
Q

What are ultrasound waves?

A

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

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19
Q

Give an example use for ultrasound waves?

A

medical or industrial imaging

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20
Q

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

A

Earthquakes
They produce both P-waves and S-waves

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21
Q

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

A

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

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22
Q

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

A

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

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23
Q

What type of spectrum do electromagnetic waves form?

A

A continuous spectrum

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24
Q

Order the types of electromagnetic radiataion from lowest to highest frequency

A

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

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25
Q

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

A

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

26
Q

What property of waves in different mediums causes refraction?

A

velocity
wave speed is slower in denser materials, causing refraction

27
Q

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

A

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

28
Q

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

A

radio waves

29
Q

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

A

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

30
Q

Where do gamma rays originate from?

A

They originate from changes in the nuclei of atoms

31
Q

What health effect can ultraviolet waves cause?

A

They can cause the skin to age prematurely
The can increase the risk of developing skin cancer

32
Q

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

A

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

33
Q

Give three practical uses for infrared radiation

A
  1. electing heaters
  2. cooking food
  3. infrared camers
34
Q

Give two practical uses for microwave radiation

A
  1. satellite communication
  2. cooking food
35
Q

give two practical uses for radio waves

A
  1. television transmission
  2. radio transmission
36
Q

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

A

refraction

37
Q

how does a convex lens form an image?

A

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

38
Q

What is meant by the focal length of a lens?

A

The distance from the lens to the principal focus

39
Q

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

A

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

40
Q

Why does magnification not have a unit?

A

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

41
Q

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

A

<—–> (rotated 90 degrees)

42
Q

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

A

> —–< (rotated 90 degrees)

43
Q

What determines the colour of visible light waves?

A

The wavelength and frequency of the light waves

44
Q

What colour of visible light has the highest frequency?

A

Blue

45
Q

What colour of visible light has the largest wavelength?

A

red

46
Q

What is meant by the term ‘specular reflection’?

A

reflection from a smooth surface in a single direction

47
Q

what is meant by the term ‘diffuse reflection’?

A

reflection from a rough surface which causes scattering

48
Q

How does a red colur filter work?

A

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

49
Q

What determines the colour of an opaque object?

A

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

50
Q

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

A

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

51
Q

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

A

white

52
Q

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

A

black

53
Q

What do all bodies (objects) emit and absorb?

A

infrared radiation

54
Q

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

A

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

55
Q

What is a perfect black body?

A

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

56
Q

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

A

none

57
Q

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

A

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

58
Q

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

A

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

59
Q

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

A

The body is absorbing and emitting radiation at the same rate

60
Q

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

A

The body is absorbing radiation faster than it is emitting it

61
Q

Give two factors that affect the temperature of the earth.

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