P4+P11 Waves, Light and Sound Flashcards

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1
Q

what’s the relationship between ANGLE OF INCIDENCE and ANGLE OF REFLECTION?

A

equal

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2
Q

how do you measure the angle of REFLECTION?

A

the angle between the normal and the reflected ray

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3
Q

characteristics of REFLECTION (4)

A

same size
same distance
laterally inverted image
virtual image

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4
Q

explain what happens during REFRACTION

A

light enters a different medium → CHANGES SPEED → BENDS (at an angle of refraction)

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5
Q

when light enters a MORE DENSE medium…

A

slows down

bends towards the normal

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6
Q

when light enters a LESS DENSE medium…

A

speeds up

bends away from normal

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7
Q

define REFRACTIVE INDEX

A

a measure of how much a material SLOWS DOWN the light that passes through it

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8
Q

how do you calculate the refractive index? (2)

A

speed of light in air / speed of light in substance

= sin (angle in air) / sin (angle in substance)

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9
Q

what is TOTAL INTERNAL REFLECTION?

what is the condition for it to occur?

A

when ALL LIGHT REFLECT and NONE REFRACT;

it occurs when angle of incidence beyond critical angle

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10
Q

what is the CRITICAL ANGLE?

A

the angle beyond which total internal reflection occurs

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11
Q

what are OPTICAL FIBERS? what does the diagram look like?

A

angle of incidence > critical angle → light always internally reflects

check diagram in notes:)

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12
Q

uses of OPTICAL FIBERS

A
  • periscope for communication

* endoscope for medicine

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13
Q

what are CONVEX LENSES?

A

converging lenses

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14
Q

what is the FOCAL POINT in convex lenses?

A

where the rays meet

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15
Q

what is the FOCAL LENGTH in convex lenses?

A

distance between center of the lens and focal point

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16
Q

how do you draw RAY DIAGRAMS?

A

1st ray: parallel to principal axis until center, through focal point

2nd ray: through the center

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17
Q

example of a REAL+DIMINISHED image

A

camera

eyes

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18
Q

example of a REAL+ENLARGED image

A

projector

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19
Q

example of a VIRTUAL+ENLARGED image

A

magnifying glass

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20
Q

what’s the difference between REAL and VIRTUAL image?

A

real can be projected onto a screen; virtual cannot

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21
Q

properties of all ELECTROMAGNETIC WAVES

A
  • transverse
  • don’t require particles to travel
  • same speed of 3x10^8 m/s
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22
Q

state all types of ELECTROMAGNETIC WAVES

in the order of wave energy, from least to most

A

radio - micro - infrared - visible light - uv - xray - gamma

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23
Q

use of RADIOWAVE

A

broadcast

radar

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24
Q

use of MICROWAVE

A

microwave oven/satellite/mobile phone communication

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25
Q

use of INFRARED RADIATION

A
thermal imaging (medical disgnosis, intruder alarm, etc.)
remote controls
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26
Q

use of VISIBLE LIGHT

A

sensation of sight

optical fiber

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27
Q

use of UV

A

disinfection

28
Q

use of X-RAY

A

x-ray pictures

checking banned materials

29
Q

use of GAMMA RAY

A

cancer treatments

30
Q

danger of MICROWAVE

A

could cause burns inside body

31
Q

danger of UV

A

sunburn

skin cancer

32
Q

danger of X-RAY

A

over-exposure damages cells

33
Q

danger of GAMMA RAY

A

kills living cells

damages DNA

34
Q

what is one way of PROTECTION against X-RAYS?

A

protective suit made of LEAD (absorbs x-rays)

35
Q

what do waves transfer?

what do waves not tranfer?

A

waves transfer ENERGY; not matter

36
Q

define a WAVE (2)

A
oscillation/vibration (1)
transfers energy (1)
37
Q

explain the difference between TRANSVERSE and LONGITUDINAL waves

A

T: direction ofvibration PERPENDICULAR to directionof energy transfer

L: direction ofvibration is PARALLEL to directionof energy transfer

38
Q

draw a diagram of TRANSVERSE WAVE, label all important parts

A

check notes:)

39
Q

draw a diagram of LONGITUDINAL WAVE, label all important parts

A

check notes:)

40
Q

T: how do you measure WAVELENGTH?

A

distance from crest to crest/trough to trough

41
Q

T: how do you measure AMPLITUDE?

A

from equilibrium to crest/trough

42
Q

L: how do you measure WAVELENGTH?

A

distance between successive compressions/rarefactions

43
Q

L:

what are COMPRESSIONS? what are RAREFACTIONS?

A

C: high particle density → high pressure

R: low particle density → low pressure

44
Q

examples of TRANSVERSE waves

A

light, water, slinky

45
Q

examples of LONGITUDINAL waves

A

sound, slinky

46
Q

what is FREQUENCY?

what unit is it measured in?

A

number of oscillations in 1s / complete waves passing a given point in 1s

hertz (Hz)

47
Q

what is WAVE SPEED? what unit is it measured in?

A

distance moved by the wave in 1s

m/s

48
Q

what’s the equation for wave speed, frequency and wavelength?

A

wave speed = frequency • wavelength

v = f • λ

49
Q

draw CIRCULAR WAVES

label the wavefronts + direction of wave spreading

A

circular wavefronts + wave spreads in all directions + wavefront perpendicular to direction that wave spreads
*check diagram in notes!

50
Q

draw PLANE WAVES

label the wavefronts + direction of wave spreading

A

vertical+parallel wavefronts + wave spreads horizontally + wavefront perpendicular to direction that wave spreads
*check diagram in notes!

51
Q

define REFLECTION in terms of waves

A

as waves bounce off a surface, they CHANGE DIRECTION

52
Q

does wave speed change in REFLECTION?

A

no

53
Q

define REFRACTION in terms of waves

A

as waves pass through a different medium, they CHANGE SPEED + DIRECTION

54
Q

define DIFFRACTION in terms of waves

A

as waves pass through a GAP, they SPREAD outwards

55
Q

draw a diagram for REFLECTION, label the wavefronts

A

check notes:)

56
Q

draw a diagram for REFRACTION, label the wavefronts

A

check notes:)

57
Q

draw a diagram for DIFFRACTION, label the wavefronts

A

check notes:)

58
Q

what type of waves are SOUND waves? can it travel in vacuum?

A

longitudinal; no

59
Q

what type of waves are LIGHT waves? can it travel in vacuum?

A

transverse; yes

60
Q

what’s the SPEED OF SOUND in air?

A

330 m/s

61
Q

what’s the SPEED OF LIGHT?

A

always 3x10^8 m/s

62
Q

what makes a sound LOUDER?

A

LARGER vibration → increased AMPLITUDE → increased loudness

63
Q

what makes a sound HIGHER PITCHED?

A

FASTER vibration → increased FREQUENCY → increased pitch

64
Q

what is the range of human hearing?

A

20 Hz - 20,000 Hz

65
Q

what are INFRASOUND and ULTRASOUND? what are their uses?

A

INFRASOUND: too LOW frequency for human to hear → detect earthquake

ULTRASOUND: too HIGH frequency for human to hear → sonar, ultrasonic scans

66
Q

draw a diagram for REFLECTION OF LIGHT, label the rays + normal + angles

A

check notes:)

67
Q

draw a diagram for REFRACTION OF LIGHT, label the rays + normal + angles

A

check notes:)