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Physics > Waves > Flashcards

Waves Flashcards

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1
Q

What is a wave

A

an oscillation (vibration) that moves through space, transferring energy from one place to another but not transferring matter

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2
Q

Mechanical waves

A

vibrations that travel through a medium (substance) (eg sound, water, seismic waves)

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3
Q

What is a transverse wave

A

Vibrate perpendicular to the direction of travel

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4
Q

What is a longitudinal wave

A

Vibrate along direction of travel

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5
Q

Amplitude

A

The distance from the centre to the peak of the wave

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6
Q

Increasing amplitude increases

A

Volume (loud/quiet)

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7
Q

Increasing frequency increases

A

pitch

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8
Q

Wave front

A

a surface containing points affected in the same way by a wave at a given time

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9
Q

Wave length

A

distance between two points one cycle apart

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10
Q

Time period

A

Time taken for one complete waveS

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11
Q

Frequency

A

Number of complete waves per second (Hz)

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12
Q

State the equation linking Frequency, wave speed and wave length with symbols and units

A

Wave speed = frequency x wave length
v = f x h (curly upside down v type h)
m/s = Hz x m

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13
Q

State the EM wave spectrum from high to low frequqncy

A

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

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14
Q

Dangers of Microwaves

A

Internal heating of body tissue
Some scientists think is causes tumours

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15
Q

Dangers of Infrared waves

A

Skin burns
Damage to the retina

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16
Q

Dangers of Ultraviolet waves

A

Damage to surface cells
Blindness
Skin Cancer
Cateracts

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17
Q

Dangers of Gamma Rays

A

Cancer
Mutations

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18
Q

Dangers of X-rays

A

Cancer
Mutations

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19
Q

Dangers of visible light

A

Damage to the retina

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20
Q

Dangers of radio waves

A

None known

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21
Q

Speed of all EM waves in a vacuum

A

3 x10 *8 m/s

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22
Q

Which colour in the rainbow has the longest wavelength

A

Red

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23
Q

Examples of longitudinal waves

A

Sound
Seismic P waves

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24
Q

Waves transfer ….. and ….. without transferring …..

A

energy , information , matter

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25
Q

State the equation linking Frequency, and time period

A

Time period = 1/Frequency

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26
Q

Doppler Effect

A

The apparent change in frequency or wavelength of a wave for an observer moving relative to its source

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27
Q

Explain why a person hears a change in pitch when a car honks its horn while moving past

A

If something is emitting waves and moving the waves at the front bunch up and the waves at the back spread out
This causes a noticeable change in wavelength and therefore its frequency as it is still going at same speed
So the sound will be higher as the car drives towards and lower as it goes away

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28
Q

Uses for Radio waves

A

Broadcasting and communication

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29
Q

Uses for microwaves

A

Cooking and satellite transmissions

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30
Q

Uses for Infrared

A

Heaters and night vision equipment

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31
Q

Uses for visible light

A

Optical fibres and photography

32
Q

Uses for Ultraviolet

A

Fluorescent lights
Tanning beds

33
Q

Uses for x-rays

A

Observing the internal structure of objects and medical applications

34
Q

Uses for gamma rays

A

Sterilizing food and medical equipment

35
Q

Ways to decreases the risk of prolonged exposure to EM waves

A

Stand as far away as possible
Stand in a different room
Try to decrease the time exposed as much as possible

36
Q

Source of radio waves

A

Radio Transmitter

37
Q

Source of infrared

A

All objects

38
Q

Source of visible light

A

lightbulb

39
Q

Source of Ultraviolet

A

Fluorescent lights

40
Q

Source of X-rays

A

Medical equipment - eg x-ray machine

41
Q

Source of gamma rays

A

Nuclear explosions

42
Q

Three similarities of EM waves

A

All travel at 3 x10*8 m/s in a vacuum
All transverse
All carry energy and information but not matter

43
Q

Name differences of EM waves

A

Different wave lengths and frequencies

44
Q

Describe what redshift means

A

Their light has moved towards the red end of the spectrum. This means that their wavelength is a lot longer than we would expect which shows that they are moving away from earth.

45
Q

Unit of energy

A

Joules (J)

46
Q

Can energy be created

A

No only transferred between stores

47
Q

8 energy stores

A

Chemical Nuclear Electrostatic Thermal Gravitational potential Kinetic Elastic Magnetic

48
Q

4 energy transfers

A

Mechanically
Electrically
By radiation
By heating

49
Q

What is unwanted energy and what is it stored as

A

Wasted energy
Thermal energy store

50
Q

Equation for efficiency

A

Efficiency = useful energy output / total energy input (J)

51
Q

In a ss key diagram what does the width of the arrow represent

A

The amount of energy
Eg 1cm could mean 10J
Then 2.5cm would mean 25J

52
Q

Describe how a power station works

A
  • Fossil fuels and biomass are burned
  • this heats the water
    -vapour spins turbine
  • which is connected to a generator
  • which generates electricity when it spins
  • this electricity goes to the transformers to produce the correct voltage
53
Q

Describe the speed of sound experiment (wooden blocks)

A
  • 100m apart
  • raise blocks above head and clap them together
  • as soon as other person sees stopwatch starts and stops when he hears it
  • note down
  • repeat method four times
    -because human reaction Time = 0.35
  • calculate the speed by 100 / time
54
Q

What is heat and what is it measured in

A

The amount of energy possessed by particles (Joules)

55
Q

What is temperature

A

The measure of how hot or cold something is (Celsius, Fahrenheit, Kelvin)

56
Q

what is the direction of energy transfer of a transverse wave

A
  • same direction as travel
57
Q

in what medium can transverse waves travel through

A

liquid or solid but not gas

58
Q

what type of seismic wave is transverse

A

seismic s waves

59
Q

what direction is the energy transfer of a longitudinal wave

A

along the direction of travel

60
Q

in what medium can longitudinal waves travel in

A

solids liquids and gases

61
Q

what is the structure of a longitudinal wave

A

compressions and rarefactions

62
Q

what type of seismic waves are longitudinal

A

seismic P waves

63
Q

how does the density and pressure of transverse and longitudinal waves change

A

transverse - constant density and pressure
longitudinal - changes in density and pressure

64
Q

what is the amplitude of a wave

A

The maximum displacement of particles from their equilibrium position

65
Q

what is the frequency of a wave

A

The number of waves passing a particular point per second

66
Q

what is the wavelength

A

The distance between a particular point on one cycle of the wave and the same point on the next cycle.

67
Q

what is the wavefront of a wave

A

where all the vibrations are in phase and the same distance from the source

68
Q

what is the Doppler effect

A

the apparent change in frequency of a wave emitted by a moving source

69
Q

dangers of microwaves

A

internal heating of body tissue

70
Q

dangers of infrared waves

A

skin burns

71
Q

dangers of ultraviolet

A

damage to surface cells and blindness

72
Q

dangers of gamma rays

A

cancer
mutations

73
Q

dangers of radio waves

A

none known

74
Q

dangers of visible light

A

damage to the retina

75
Q

dangers of x rays

A

cancer and mutations

76
Q

law of reflection

A

angle of incidence = angle of refraction

Physics (13 decks)

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