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Physics > Waves and Light > Flashcards

Waves and Light Flashcards

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1
Q

What is White Light?

A

White light from the Sun is a mixture of colours, each with a different frequency.

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2
Q

What can we do with a Prism?

A

You can use a prism to split (or disperse) white light into a spectrum of colours

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3
Q

Name the All the colours in the spectrum

low frequency to high frequency

A 
red
orange
yellow
green
blue
indigo
violet
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4
Q

What does Disperse mean?

A

The splitting of white light to form the colour spectrum

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5
Q

Name the 3 colours our eyes can detect:

A

Red, Green and blue

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6
Q

How can we see more than 3 colours?

A

By combining the 3 colours ,We can perceive many different colours

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7
Q

Give an example for dispersion:

A

By mixing red light and green light, for example, we can see yellow

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8
Q

What happens if we mix all Red, Green and blue light?

A

If all three are mixed together we see white light

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9
Q

How do objects have different colours?

A

Objects absorb and reflect light differently. A lemon reflects yellow light, all the other colours are absorbed and so are not seen by our eyes.

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10
Q

What would happen if the light ray is travelling along the Normal

A

if a light ray travelling along the normal hits a mirror, it is reflected straight back the way it came. The reflection of light from a flat surface such as a mirror is called specular reflection – light meeting the surface in one direction is all reflected in one direction.

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11
Q

What is the speed of light waves in a vaccum?

A

_ ___
\ / | | | 8
/ | | |
\ | | |
_ / X | | ___| m/s

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12
Q

What are the Primary colours (for light)?

A

Red,green and blue

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13
Q

WHAT ARE THE SECONDARY COLOURS FOR LIGHT?

A

Yellow, Cyan , Magneta

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14
Q

Name 6 features of a camera

A 
Converging lens
Shutter
Focal Point
Focusing screw
Aperture
Photo sensitive surface
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15
Q

What does the converging lens do?

A

They refract light rays so they can meet at 1 point

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16
Q

What does the shutter do?

A

a device that allows light to pass for a determined period, exposing photographic film

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17
Q

What does the focal point do?

A

the point at which rays or waves meet after reflection or refraction

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18
Q

What does the Focusing screw do?

A

used to adjust the focus

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19
Q

What does the Aperture do?

A

Controls How much light enters the camera

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20
Q

What does the Photo sensitive surface do?

A

Substance that changes in some way when it absorbs light, for example leading to a chemical or electrical change.

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21
Q

How did an Old fashioned Cameras produce an image?

A

In an old-fashioned camera, the photo-sensitive material was camera film. When the film absorbed light, a chemical change produced an image in the film, called the ‘negative’. This was used to produce a photograph on photo-sensitive paper.

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22
Q

How does a modern Camera Produce an Image?

A

In a modern camera or the camera in a mobile phone, the photo-sensitive material produces electrical impulses, which are used to produce an image file. This can be viewed on the screen, or its information sent to a printer

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23
Q

WHAT ARE THE 6 FEATURES OF THE EYE?

A 
Iris
Pupil
Retina
Optic nerve
Lens
Cornea
24
Q

Iris=

A

The iris controls the amount of light that enters the eye by opening and closing the pupil.

25
Q

Pupil=

A

controlling the amount of light entering the eye

26
Q

Retina=

A

receive light that the lens has focused, convert the light into neural signals

27
Q

Optic nerve=

A

to transfer visual information from the retina in your eye to the visual centers of your brain in the form of impulses, allowing your brain to translate these impulses as images in your head.

28
Q

Lens=

A

along with the cornea, helps to refract light to be focused on the retina.

29
Q

Explain One Way Superposition can be Demonstrated:

A

A ripple tank is a tank full of water in which a vibrating needle produces a stream of ripples. We can watch superposition and reflection in the water waves.

30
Q

How do our Ears Detect Sound

A

An ear has an eardrum inside, connected to three small bones. The vibrations in the air make the eardrum vibrate, and these vibrations are passed through the three small bones (called ossicles) to a spiral structure called the cochlea. Signals are passed from the cochlea to the brain through the auditory nerve, and our brain interprets these signals as sound.

31
Q

How does a Microphone Work?

A

Microphones contain a diaphragm, which does a similar job to an ear drum. The vibrations in air make the diaphragm vibrate, and these vibrations are changed to electrical impulses. In the lab, the electrical impulses can be sent to an oscilloscope, which represents them as a graph on a screen.

32
Q

the greater the amplitude,

A

the louder the sound

33
Q

the closer together the waves are and

A

the higher the pitch

34
Q

Explain how the Clap-echo method works:

A

This method involves measuring the time taken for you to hear an echo from a sharp clap. You stand a long distance from a wall, clap, and listen for the echo. The distance travelled is twice the distance from you to the wall (because the sound has to travel to the wall and back

35
Q

Name the 8 features of an ear

A 
Pinna
Ear Canal
Eardrum
Hammer
Anvil
Stirrup
Cochlea
Auditory Nerve
36
Q

What is the Microphone?

A

The microphone is a device that converts sound waves into electrical signals.

37
Q

Examples of longitudinal waves include:

A

sound waves
ultrasound waves
seismic P-waves

38
Q

How are Sound Waves Detected?

A

by Diaphragms in Microphones

The vibrations in a sound wave make a sensitive diaphragm vibrate inside the microphones . The microphones convert the vibrations to electrical signals .

Don’t NEED TO KNOW BUT

Another device can record the electrical signals so that the sound can be reproduced later

39
Q

TRANSVERSE WAVES=

A

OSCILLATIONS ARE PERPENDICULAR TO THE DIRECTION OF WENERGY TRANSFER

40
Q

LONGITUDINAL WAVES=

A

OSCILLATIONS THAT ARE PARALELL TO THE DIRECTION OF ENERGY TRANSFER

41
Q

High freq=
low freq=

Increase the current=

A

High freq= higher pitch sound
low freq= lower pitch sound

Increase the current= increase the amplitude of the vibration= increases the volume of the sound

42
Q

5 steps of Hearing:

A

Objects Vibrate

Air vibrates

Ear Drum vibrates

Ear bones vibrate

Hairs vibrate in the cochlea, sending a message to the brain (along the auditory nerve)

43
Q

What is a medium

A

Any substance that light or any other wave travels through is called a medium

44
Q

Why will sometimes when light enters a glass block (for eg) , the direction of light will not change?

A

Because the light rays enters the glass block travelling straight on/along the normal

45
Q

Why do rough surfaces look dull?

A

Because the light is reflected back in lots of different directions (scattered). This is diffuse reflection/diffuse scattering

46
Q

What is Dispersion?

A

Spreading out of the different wavelengths of light, caused by refraction of light as it passes through a prism

47
Q

Why can White objects appear different colours than white in filter and coloured light?

A

Because white objects reflect all colours

48
Q

Explain why removing air makes sound STOP

A

Sound can’t travel in a vacuum as there no particles to pass on the vibrations

49
Q

Name 2 equations that can find the speed/wave speed

A

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

speed(m/s) =Distance (m) ÷ Time(s).

Remember to convert

50
Q

Name the equation that can solve the distance

A

distance= speed x time

51
Q

Remember that an echo is divided by 2

A

Ok

52
Q

Cornea=

A

The cornea is the transparent part of the eye that covers the front portion of the eye. It covers the pupil ,iris .The cornea’s function is to refract light. The cornea is responsible for focusing most of the light .

53
Q

What do Loudspeakers do?

A

Loudspeakers recreate sound wave

An electrical signal is fed into a loudspeaker. The signal causes the diaphragm to vibrate. This makes the air vibrate, producing sound waves. (microphone in reverse)

54
Q

Name 3 examples of diaphragms

A 
a thin paper
or
a plastic sheet
or
aluminium
55
Q

Explain why Humans cant hear Ultrasound

A

Ultrasound waves have a higher pitch/frequency than the normal auditory range of humans

56
Q

What can White light do?

A

White light can be split up into a spectrum of colours using a prism, a triangular block of glass or Perspex

Light is refracted when it enters the prism, and each colour is refracted by a different amount. This means that light leaving a prism is spread out into its different colours

57
Q

How do you find out frequency ? NTK

A

Frequency/Hz = number of waves divide by time/s

Physics (3 decks)

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