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waves Flashcards

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1
Q

Define wavelength.

A

The distance between the same points on two consecutive waves.

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2
Q

Define amplitude.

A

The distance from the equilibrium line to the maximum displacement (crest or trough).

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3
Q

Define frequency.

A

The number of waves that pass a single point per second.

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4
Q

Define a period.

A

The time taken for a whole wave to completely pass a single point.

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5
Q

What is the equation for velocity?

A

Frequency x wavelength.

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6
Q

What is the equation for a period?

A

1
——————
Frequency

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7
Q

Increased frequency =

A

Increased velocity.

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8
Q

Increased wavelength =

A

Increased velocity.

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9
Q

A period is inversely proportional to…

A

Frequency.

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10
Q

A smaller period =

A

Higher frequency and greater velocity.

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11
Q

What are 2 examples of transverse waves?

A

~Light waves
~Electromagnetic waves

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12
Q

Do transverse waves have peaks and troughs or compressions and rarefactions?

A

Peaks and troughs.

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13
Q

In transverse waves, vibrations are…

A

At right angles to the direction of travel.

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14
Q

What is an example of a longitudinal wave?

A

Sound waves.

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15
Q

Do longitudinal waves have peaks and troughs or compressions and rarefactions?

A

Compressions and rarefactions.

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16
Q

In longitudinal waves, vibrations are…

A

In the same direction as the direction of travel.

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17
Q

What must a surface be for waves to reflect off of it?

A

Flat.

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18
Q

The smoother the surface…

A

The stronger the reflected wave.

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19
Q

Why do rough surfaces appear matte and not reflective?

A

As they scatter light in all directions.

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20
Q

Angle of incidence =

A

Angle of reflection.

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21
Q

Electrons absorb the light energy, then…

A

Re-emit it as a reflected wave.

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22
Q

The more transparent a material is…

A

The more light will pass through it.

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23
Q

If the frequency of the light matches the electron’s energy levels…

A

Light will be absorbed by the electrons and won’t be re-emitted.

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24
Q

If a material appears green…

A

Only green light has been reflected and the rest of the frequencies in visible light have been absorbed.

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25
Q

What do sound waves cause when they travel through solids?

A

Vibrations.

26
Q

Compression forces the eardrum…

A

Inward.

27
Q

Rarefactions forces the eardrum…

A

Outward due to pressure.

28
Q

What do small bones in the ear do?

A

Amplify sound waves.

29
Q

The eardrum and small bones vibrate at…

A

The same frequency as the sound wave.

30
Q

What happens when hairs attuned to the specific frequency move a lot?

A

An electrical impulse is released to the brain where the brain interprets this to a sound.

31
Q

What is the normal human hearing range?

A

20Hz - 20kHz.

32
Q

Hairs attuned to higher frequencies in the cochlea can die or be damaged by…

A

~Constant loud noise
~Changes in the inner ear
~Smoking, chemotherapy and diabetes

33
Q

Which type of sound can humans not hear?

A

Ultrasound.

34
Q

What is the opposite of ultrasound?

A

Infrasound. (seismic waves)

35
Q

What is a seismic wave?

A

A sound wave with a frequency that is less than 20Hz.

36
Q

What is a P wave?

A

A longitudinal wave which can pass through solids and liquids.

37
Q

What is an S wave?

A

A transverse wave that moves slow and can only pass through solids.

38
Q

What do electromagnetic waves not need to move?

A

Particles.

39
Q

In space all electromagnetic waves have…

A

The same velocity.

40
Q

Electromagnetic waves can transfer…

A

Energy from a source to an absorber.

41
Q

What is an example of an energy transfer from a source to an absorber?

A

A microwave to food.

42
Q

In electromagnetic waves, as wavelength decreases…

A

Frequency must increase.

43
Q

In electromagnetic waves, as frequency increases…

A

The energy of the wave increases.

44
Q

If entering a denser material, refraction…

A

Bends towards the normal.

45
Q

If entering a less dense material, refraction…

A

Bends away from the normal.

46
Q

Substances will absorb, transmit, refract or reflect certain EM waves depending on…

A

Wavelength.

47
Q

What are radio waves produced by?

A

Oscillations in electrical circuits.

48
Q

When radio waves are absorbed, they create…

A

An alternating current at the same frequency.

49
Q

Why are radio waves used for TV?

A

As they have a long wavelength and can travel far without losing quality.

50
Q

Why are microwaves used for satellite communication?

A

As they can penetrate the atmosphere.

51
Q

Why are infrared waves used for cooking food?

A

As they transfer thermal energy.

52
Q

Why are visible rays used for fibre optics?

A

As they have the best reflection / scattering in glass.

53
Q

Why are UV rays used in tanning and energy efficient lamps?

A

They radiate the least amount of heat but more energy.

54
Q

Why are X-ray waves used in medical imaging and treatment?

A

As they are very high in energy and can penetrate material easily.

55
Q

Concave lenses are thinner…

A

At the centre.

56
Q

Convex lenses are wider…

A

At the centre.

57
Q

Concave lenses spread…

A

Light outwards.

58
Q

Convex lenses focus…

A

Light inwards.

59
Q

In concave lenses, light appears to have come from…

A

The focal point.

60
Q

In convex lenses, horizontal rays focus…

A

Onto the focal point.

physics (7 decks)

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