Waves Flashcards

(26 cards)

1
Q

What is the order of waves?

A

radio, microwaves, infrared, visible, ultraviolet, x-ray, gamma

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2
Q

What is a transverse wave?

A

the oscillations are at right angles to the direction the waves are travelling (s-shape)

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3
Q

What is a longitudinal wave?

A

the oscillations are parallel to the travelling direction (backwards and forwards)

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4
Q

what type of wave are:

  • electromagnetic
  • sound waves
  • water waves?
A

transverse, longitudinal, transverse (actually a combination)

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5
Q

what is amplitude?

measured in?

A

maximum displacement from the equilibrium position of the substance the wave is moving in
metres (m)

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6
Q

what is frequency?

symbol + measured in?

A

number of complete wave cycles in 1 second

f; hertz (Hz)

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7
Q

what is wavelength?

symbol and measured in?

A

distance from one point on a wave to the next identical point on the next wave
λ; metres (m)

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8
Q

what’s the period of a wave?

A

T; time taken for the source to produce one complete wave (in seconds)

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9
Q

what’s an oscillation

A

repetitive to and fro movement

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10
Q

what is it in a wave that oscillates?

A

the medium it is travelling through

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11
Q

what’s the formula linking wave speed, frequency and wavelength?

A

v = f x λ

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12
Q

what’s the formula for frequency & the time period?

A

f = 1 ÷ T

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13
Q

what rule links the angle i and the angle r in light rays reflecting?

A

i = r

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14
Q

where are the i and r angles?

A

between the reflected / incident ray and the normal

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15
Q

how do plane waves reflect off a concave (curving in) barrier?

A
  • waves more curved than the barrier
  • brought to a focus
  • no change in wavelength
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16
Q

how do circular waves reflect off a plane (flat) barrier?

A
  • waves appear to be coming from a virtual source as far behind the barrier as the true source is in front
  • no change in wavelength
17
Q

what does the speed of a wave depend on?

A

the properties of the medium it is travelling through

18
Q

what can the change of speed at a boundary cause?

how can you tell the speed has changed?

A

a change of direction of travel at the boundary (refraction)

the waves will bunch up / space out

19
Q

where does the light bend when travelling from air into glass?

A

towards the normal

20
Q

what does frequency have to do

A

stay the same

21
Q

what happens if the waves cross the boundary at right angles?

A

no change of direction

22
Q

radio waves facts (2)

A
  • produced and transmitted by very rapidly alternating electric currents
  • received by aerials where the those currents are induced by the radio waves
23
Q

microwaves facts (6)

A
  • wavelengths range from mm to cm
  • can cook things containing water
  • the water molecules become agitated because their frequencies coincide
  • used in mobiles
  • travel through air well
  • smaller wavelength = more detail
24
Q

infrared facts (8)

A
  • emitted by all things colder than the temp. for emitting visible light
  • all things give out radiation as infrared
  • can make temp. map
  • can be reflected
  • can/can’t pass through different things to visible light
  • not good at passing through air
  • goes past red on colour spectrum
  • used in communication + thermal imaging
25
visible light facts (3)
- white light = combination of all frequencies - when colour a is seen, all other colours are absorbed while a is reflected - black = absence of light
26
ultraviolet light (3)
- can have harmful ionising effect - fluorescent chemicals absorb uv light and emit it as visible light (eg washingup powder) - uses: security marking, tooth whitening