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Light & Sound Flashcards

1
Q

What type of waves are light waves?

A

Light waves are transverse waves like all electromagnetic waves.

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2
Q

How do light waves transmit energy?

A

They transmit energy through vibrations that move up and down at right angles to the direction of wave travel just like a wave at sea.

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3
Q

What can light waves do?

A

All light waves can be reflected and refracted.

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4
Q

What happens during reflection of light waves?

A

Reflection is when the light wave bounces off an object and travels in the other direction.

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5
Q

What happens during refraction of light waves?

A

Refraction is when the light wave passes through another material of a different density and changes speed as it passes through it.

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6
Q

What is reflection?

A

Reflection is when waves bounce off a surface.

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7
Q

Why is the reflection of light waves important?

A

The reflection of light waves allows us to see the objects around us.

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8
Q

Can sound waves be reflected?

A

Yes, sound waves can be reflected and this is what happens when you hear an echo.

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9
Q

What happens when a wave hits a surface at a certain angle?

A

It will be reflected at exactly the same angle.

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10
Q

What is the angle of incidence?

A

The angle of incidence is measured between the incoming light ray (the incident ray) and the normal.

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11
Q

What is the normal?

A

The normal is an imaginary line at 90° to the reflecting surface and is drawn as a dotted line.

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12
Q

What is the angle of reflection?

A

The angle of reflection is measured between the reflected light ray and the normal.

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13
Q

What happens when waves travel through different materials?

A

Waves travel at different speeds depending on the material they are travelling through.

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14
Q

What is refraction?

A

Refraction is the change of speed when a wave enters a new substance.

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15
Q

Why do waves travel slower in denser materials?

A

Denser materials have particles that are closer together, making it more difficult for waves to travel through, so it takes longer to pass between the particles.

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16
Q

What happens when light passes from air into glass?

A

The wave speed of light decreases when it passes from air into glass.

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17
Q

Why does a straw look bent in a glass of water?

A

Light travels faster through air than water, so the path of light bends as it enters the water.

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18
Q

What happens when a wave slows down?

A

The wavelength decreases while the frequency stays the same.

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19
Q

What happens to the wavelength when the wave speed decreases?

A

The wavelength must also decrease.

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20
Q

What happens on a ray diagram when light is refracted?

A

The refracted ray will be emitted at a different angle to the incident ray.

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21
Q

What happens if the second material is more dense than the first?

A

The refracted ray bends towards the normal, making the angle of refraction smaller than the angle of incidence.

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22
Q

What happens if the second material is less dense than the first?

A

The refracted ray bends away from the normal, making the angle of refraction larger than the angle of incidence.

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23
Q

What determines how quickly light travels?

A

Light travels at different speeds depending on the medium it is travelling through.

24
Q

Where does light travel the fastest?

A

Light travels quickest through space or a vacuum where there are no particles to slow it down.

25
How does light travel in air and denser materials?
It travels a little slower in air and even more slowly in denser materials such as glass or water.
26
What is the refractive index?
The refractive index is a measure of the change in speed of light as it passes from a vacuum into a certain material.
27
What does the refractive index tell us?
The higher the refractive index, the more the speed changes as light enters the material.
28
How does the refractive index of glass compare to that of water?
The refractive index of glass is higher than that of water (1.5 in glass compared to 1.3 in water), meaning light travels slower in glass than in water.
29
How can we calculate the refractive index?
We can calculate the refractive index by measuring the angles of incidence and refraction.
30
What is Snell’s law?
Snell’s law describes how to calculate the refractive index using the angles of incidence and refraction.
31
What happens when light passes into a denser medium?
The light waves slow down and the angle of refraction is smaller than the angle of incidence with the refracted ray moving closer to the normal.
32
What happens when light passes into a less dense medium?
The light wave speeds up and the angle of refraction is greater than the angle of incidence as the refracted ray moves away from the normal.
33
What is the critical angle?
The critical angle is when the angle of refraction is equal to 90° and the angle of incidence is called the critical angle.
34
What happens if the angle of incidence is greater than the critical angle?
If the angle of incidence is greater than the critical angle, no light passes through the medium – it is totally internally reflected.
35
How does the refractive index affect the critical angle?
The higher the refractive index, the lower the critical angle, meaning the harder it is for light to pass through the material, the more likely the light ray is to be totally internally reflected.
36
Why are diamonds so sparkly?
Diamonds have a high refractive index and a low critical angle, meaning when light hits a diamond, it is reflected inside the gemstone rather than passing out, making the diamond sparkle.
37
Where is total internal reflection used?
Total internal reflection is used in optical fibres and prisms.
38
Why are optical fibres made so narrow?
Optical fibres are made so narrow that the incident light ray always hits the fibre at an angle greater than the critical angle.
39
What is the critical angle for glass optical fibres?
If the optical fibre is made of glass, the critical angle will be around 42°.
40
What happens when incident light hits the back of a prism?
When the incident light ray hits the back of the prism, it will be internally reflected at a 90° angle.
41
How does the light ray emerge from the prism?
The light ray emerges from the prism along a normal and continues out of the surface of the prism.
42
How can two prisms function as a periscope?
Two prisms can be set up like this to function as a periscope.
43
What type of waves are sound waves?
Sound waves are longitudinal waves meaning they travel by particles vibrating side to side in the same direction as the direction of wave travel.
44
What are the two main parts of sound waves?
Sound waves are made up of areas of compression where the particles are bunched up together and areas of rarefaction where the particles are spread out.
45
Can sound waves be reflected and refracted?
Yes like all other waves sound waves can be reflected and refracted.
46
What is the frequency range of human hearing?
The frequency range of human hearing is between 20 - 20,000Hz
47
How does the range of human hearing change with age?
Our range of hearing decreases as we get older so there are frequencies that only younger people can hear that older individuals will be completely deaf to.
48
What are frequencies higher than 20,000Hz called?
ultrasound and are outside the range of human hearing.
49
What is an oscilloscope?
An oscilloscope is a machine which shows the shape of sound waves.
50
How is the oscilloscope connected to a sound source?
It is connected to a microphone which detects the sound and converts it to an electrical signal.
51
What can we determine from the oscilloscope trace?
We can use the oscilloscope trace to determine information about the sound such as its volume and frequency.
52
What does the amplitude of a wave correspond to?
The amplitude of a wave corresponds to its volume - the higher the amplitude, the louder the sound.
53
What type of sound waves would an iron maiden concert produce?
An iron maiden concert will be releasing higher amplitude sound waves than chanting monks.
54
What does the frequency of a wave correspond to?
The frequency of a wave corresponds to its pitch - the higher the frequency, the higher the pitch.
55
How do men’s and women’s voices differ in terms of frequency?
Men’s voices have a lower pitch so the sound wave will have a lower frequency, with fewer cycles displayed on the screen.

Physics (21 decks)

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