Paper 2 - 6 Waves Flashcards

1
Q

What do waves transfer?

A

Energy

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2
Q

What are the two types of wave?

A

Transverse and longitudinal

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3
Q

Describe a transverse wave

A

The vibrations of the wave are perpendicular to the direction in which energy is transferred

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4
Q

Give some examples of transverse waves

A

Ripples on a water surface. Any wave in the electromagnetic spectrum

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5
Q

Describe a longitudinal wave

A

The vibrations of the wave are parallel to the direction in which energy is transferred. Longitudinal waves show areas of compression and rarefaction.

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6
Q

Give some examples of longitudinal waves

A

Sound waves. Ultrasound. Infrasound. P-waves.

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7
Q

Define amplitude

A

The amplitude of a wave is the maximum displacement of a point on a wave away from its undisturbed position. It shows us how much energy a wave has.

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8
Q

Define wavelength

A

The wavelength of a wave is the distance from a point on one wave to the equivalent point on the adjacent wave. Measured in meters

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9
Q

Define frequency

A

It is the number of waves that pass a point per second. Measured in hertz (Hz)

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10
Q

Define period (T)

A

Its the time for one exact wave to pass a point. Measured in seconds

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11
Q

State the wave equation with all units

A

wave speed (m/s) = frequency (Hz) x wavelength (m)

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12
Q

Describe an experiment to find the speed of sound through air

A

Measure a distance of 100 m from a wall. Hit two blocks together to make a sound and start timing. Stop timing when the hear the reflected sound (echo). Divide the time recored by 2. use the equation Speed = distance / time

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13
Q

Describe a method to measure the speed of ripples on a water surface.

A

Set up a ripple tank. Find the wavelength by using a ruler to measure across 10 wavelengths. Divide the answer by 10 to find 1 wavelength. Use a stopwatch and count the number of waves produced in 10 seconds. Dived the answer by 10 to find the frequency. Use the equation speed = wavelength x frequency

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14
Q

What can happen to waves when they reach a boundary between two materials?

A

They can be reflected. They can be absorbed (this will cause a small temperature rise.). They can be transmitted (they will pass through)

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15
Q

What is the law of reflection

A

The angle of incident = angle of reflection for a flat plain mirror.

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16
Q

What is refraction?

A

When a wave travels from one medium to another and changes direction.

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17
Q

Why does refraction take place?

A

The change in medium means a change in density which caused a change in speed.

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18
Q

When a sound wave moves from a more dense to a less dense substance, what is the effect on wave speed, frequency and wavelength?

A

Wave speed - decreases Frequency - same Wavelength - decreases

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19
Q

When a sound wave moves from a less dense to a more dense substance, what is the effect on wave speed, frequency and wavelength?

A

Wave speed - increases Frequency - same Wavelength - increases

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20
Q

State the normal human hearing range

A

From 20 Hz to 20 kHz

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21
Q

How do we detect sound waves?

A

Within the ear, sound waves cause the ear drum and other parts to vibrate. These vibrations are converting into an electrical signal which is passed onto the brain.

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22
Q

Why do humans have a limited range of frequencies they can detect?

A

The conversion of sound waves to vibrations of solids works over a limited frequency range. This restricts the limits of human hearing.

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23
Q

What is the effect of a louder sound on the ear drum?

A

Larger vibrations

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24
Q

What is the effect of a higher pitched sound on the ear drum?

A

Faster vibrations

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25
Q

What is a ultrasound?

A

Ultrasound waves have a frequency higher than the upper limit of hearing for humans (20000 Hz)

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26
Q

How can ultrasound be used for medical and industrial imaging?

A

Ultrasound waves are partially reflected and partially transmitted when they meet a boundary between two different media. The time taken for the reflections to return to the detector can be used to determine how far away such a boundary is.Distance = speed x time

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27
Q

What are seismic waves

A

Waves produced by Earthquakes

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28
Q

What type of waves are P-waves?

A

longitudinal

29
Q

What type of waves are S-waves?

A

Transverse

30
Q

Which earthquake waves cannot travel through the liquid core?

A

S-waves as they are transverse

31
Q

What is a shadow zone?

A

An area where no p waves or s waves are detected

32
Q

What does a shadow zone show us?

A

There must be a liquid core because:P waves are refracted at the core mantle boundary S waves can’t travel through the liquid core

33
Q

State the waves that make up the electromagnetic spectrum, in order of increasing wavelength

A

Radio waves Microwaves Infrared Visible light Ultraviolet X-rays Gamma rays

34
Q

What do all electromagnetic waves have in common?

A

They are all transverse waves They can all travel through a vacuum They all travel at the speed of light through a vacuum

35
Q

How are radio waves produced?

A

By an oscillating electrical current.

36
Q

What happens when radio waves are absorbed by an aerial?

A

When radio waves are absorbed they may create an alternating current with the same frequency as the radio wave itself

37
Q

What are the dangers of ultraviolet waves

A

Can age skin prematurely Can burn skin which can lead to skin cancer Damage eyes which can lead to blindness

38
Q

What are the dangers of X-rays and gamma rays?

A

X-rays and gamma rays are ionising radiationLow doses can damage DNA and cause cancerLarge doses can kill cells

39
Q

State some uses of radio waves

A

television and radio, these waves stay within the earths atmosphere.

40
Q

State some uses of microwaves

A

Satellite communications eg mobile phone and satellite TV. Microwaves can travel to space and back.Cooking food.

41
Q

State some uses of infrared

A

electrical heaters, cooking food, infrared cameras

42
Q

State some uses of visible light

A

fibre optic communications

43
Q

State some uses of ultraviolet

A

energy efficient lamps, sun tanning

44
Q

State some uses of X-rays and Gamma rays

A

medical imaging and treatments.

45
Q

How does a lens work?

A

A lens forms an image by refracting light to a focal point

46
Q

When describing the nature of an image formed the key words to use are?

A

Real or virtual Magnified or diminished Upright or inverted

47
Q

What are the units of magnification

A

no units as it is a ratio

48
Q

In a ray diagram the symbol for a convex lens will be represented by?

A

A vertical line with arrow heads at each end

49
Q

In a ray diagram the symbol for a concave lens will be represented by?

A

A vertical line with inverted arrow heads at each end

50
Q

Describe specular reflection

A

Reflection from a smooth surface in a single direction is called specular reflection

51
Q

Describe diffuse reflection

A

Reflection from a rough surface causes scattering: this is called diffuse reflection.

52
Q

Explain how a red filter works

A

A red filter will allows the red wavelength to be transmitted whilst the wavelengths of all the other colours will be absorbed.

53
Q

Describe how we can see a blue object.

A

A blue object will reflect treble wavelengths into our eyes. All the other wavelengths and colours will be absorbed.

54
Q

Describe how we can see a white object.

A

If all wavelengths are reflected equally the object appears white.

55
Q

Describe how we can see a black object.

A

If all wavelengths are absorbed the objects appears black.

56
Q

Objects that transmit light are called?

A

transparent or translucent

57
Q

What is the relationship between the temperature of an object and the amount of infrared radiation it emits?

A

The hotter the body, the more infrared radiation it radiates in a given time.

58
Q

Describe a perfect black body

A

A perfect black body is an object that absorbs all of the radiation incident on it. A black body does not reflect or transmit any radiation. Since a good absorber is also a good emitter, a perfect black body would be the best possible emitter.

59
Q

How can a body be at a constant temperature?

A

A body at constant temperature is absorbing radiation at the same rate as it is emitting radiation.

60
Q

How can the temperature of a body increase?

A

The temperature of a body increases when the body absorbs radiation faster than it emits radiation.

61
Q

How can the temperature of a body decrease?

A

The temperature of a body decreases when the body absorbs radiation slower than it emits radiation.

62
Q

What factors affect the temperature of the Earth?

A

The temperature of the Earth depends on many factors including: the rates of absorption and emission of radiation, reflection of radiation into space.

63
Q

When light slows down which direction does it refract?

A

Towards the normal

64
Q

When light speeds up which direction does it refract?

A

Away from the normal

65
Q

What surface is the best emitter of infrared radiation?

A

Matt black surfaces

66
Q

What surface is the worst emitter of infrared radiation?

A

Silver (shiny) surfaces

67
Q

What surface is the best absorber of infrared radiation?

A

Matt black surfaces

68
Q

If an object’s temperature is higher, what will happen to the infrared radiation it’s emitting?

A

Higher temperature -> more infrared radiation emitted in a given time