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Physics > waves > Flashcards

waves Flashcards

1
Q

what are waves produced by

A

oscillating or a vibrating system

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2
Q

what are oscillation and vibration

A

repetitive motions about an equilibrium in a closed path

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3
Q

what are progressive waves

A

is a wave that travels with time along the direction of propagation of the wave

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4
Q

what are stationary waves

A

a wave where the profile of the wave does not propagate with time

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5
Q

how can stationary waves be produced

A

through musical instruments such as guitars

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6
Q

list 3 points for mechanical waves

A

requires medium to transfer energy from one point to another

made up of vibrating particles of a medium

water waves, sound waves, and seismic waves on the surface of the earth are mechanical waves

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7
Q

list 3 points for electromagnetic waves

A

does not require a medium

made up if oscillating electric and magnetic fields perpendicular to one another

radio waves, light waves and gamma rays are examples of them

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8
Q

compare transverse waves and longitudinal waves

A

particles of the medium vibrate in the direction perpendicular to the direction of the propagation of the wave

particles of the medium vibrate in the direction parallel to the direction of propagation of the wave

made up of crests and troughs

made up of consecutive compressions and rarefactions

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9
Q

what is the definition of amplitude, A

A

maximum displacement of a particle from its equilibrium position

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10
Q

what is the definition of period, T

A

the time taken by a particle to make one complete oscillation or by a source to produce one complete cycle of wave

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11
Q

what is the definition of frequency, f

A

number of complete oscillations made by a particle or number of cycles of waves produced by a source in one second

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12
Q

what is the definition of wavelength, lambda

A

distance between two consecutive points in phase

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13
Q

what is the definition of wave speed, v

A

distance travelled per second by a wave profile

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14
Q

what is the formula for speed of wave

A

v = f lambda

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15
Q

sketch the graph of displacement against time and distance for waves

A

d

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16
Q

what are the two dippers used in ripple tank

A

plane dipper and spherical dipper

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17
Q

how does oscillating systems experience energy loss

A

external damping
loses energy to overcome friction to sir resistance
internal damping
loses energy because stretching and compression if the vibrating particles in the system

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18
Q

what is damping

A

damping is the reduction in amplitude in an oscillating system due to loss of energy.
during damping, the oscillating frequency remains constant while the oscillating amplitude decreases.

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19
Q

how can the effect of damping be overcome

A

applying periodic external force on the oscillating system. the periodic external force transfers energy into the oscillating system to replace the energy lost.
the system is said to be in forced oscillation

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20
Q

how does an oscillating system be at resonance

A

when a periodic force is applied to an oscillating system at its natural frequency

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21
Q

what happens during resonance

A

the system oscillates with its natural frequency

system oscillates with maximum amplitude

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22
Q

what is wavefront

A

a surface over in which the wave is constant

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23
Q

what happens to angle of incidence and angle of reflection when wave is reflected

A

angle of incidence = angle reflection

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24
Q

what happens to the wavelength after reflection of wave

A

no change

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25
Q

what happens to the frequency when wave is reflected

A

no change

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26
Q

what happens to the direction of propagation when wave is reflected

A

changes with the condition that the angle of incidence is the same as angle of reflection

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27
Q

try to draw the diagram for reflection of water waves

A

kn

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28
Q

give 4 applications of reflection of waves in daily life

A

ultrasonic waves
used in medical field to examine a foetus or other internal organs

radio waves
from communication satellites are reflected by the parabolic dish and focussed into the antenna in the feed horn

technology of ultrasonic of reflection
which is known as sonar helps to detect areas which have a lot of fish. transducer transmit waves into the water and these waves are reflected by the fish to the transducer

patterns of reflected sound waves caused by different rocks
enable the location, depth and structure of the sea bed which contain sources if natural gas to be identified

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29
Q

solve problem involving reflected waves

A

sa

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30
Q

what does refraction of waves mean

A

the change in direction if propagation of waves caused by the change in the velocity of waves when the waves propagate from one medium to another

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31
Q

what influence speed of water waves

A

depth of water

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32
Q

what influence speed of sound waves

A

density of air

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33
Q

what influence speed of light wave

A

optical density if medium

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34
Q

what happens to the angle of incidence and angle of refraction when waves move from deep water region to shallow water region

A

angle of incidence > angle of refraction

35
Q

what happens to the angle of incidence and angle of refraction when waves move from shallow water region to deep water region

A

angle of incidence < angle refraction

36
Q

what happens to the wavelength when waves move from deep water region to shallow water region

A

decreasing

37
Q

what happens to the wavelength when waves move from shallow water to deep water region

A

increasing

38
Q

what happens to the frequency when waves move from deep water region to shallow water region

A

no change

39
Q

what happens to the frequency when waves move from shallow water region to deep water region

A

no change

40
Q

what happens to the wave speed when waves move from deep water region to shallow water region

A

decreasing

41
Q

what happens to the wave speed when waves move from shallow water region to deep water region

A

increasing

42
Q

what happens to the direction if propagation when waves move from deep water region to shallow water region

A

reflected towards the normal

43
Q

what happens to the direction of propagation when waves move from deep water region to shallow water region

A

reflected away from the normal

44
Q

try to draw the diagram for the refraction of plane water waves

A

aa

45
Q

why cant an observer hear clearly during daytime

A

air that is closer to the surface of the earth is hotter than the air above
sound moves faster in hot air than in cold air. as such, sound reflected away from the ground
thus, an observer cant hear clearly during the day

46
Q

why can an observer hear more clearly during the night

A

during the night, air that is closer to the surface of the earth is colder. Sound is refracted towards the ground.

47
Q

why the amplitude of waves at bay is smaller that at the cape

A

the cape is the shallow water region while the bay is the deep water region. Away from the shoreline, the wavefront of the water is almost straight and parallel because water waves move at a uniform speed.

when the wavefront of the water propagates to the cape, the speed of the water waves decreases causing the wavelength to be shorter. Wavefront of water approaching the bay moves at a higher speed and the wavelength is longer. This causes the wavefront to curve and follow the shape of the shoreline.

refraction of water waves causes water wave energy to converge towards the cape. Water wave energy diverges from the bay and spread out to a wider region. Thus, the amplitude of waves at bay is smaller than at the cape.

48
Q

what is refraction of waves caused by

A

the change is speed of waves

49
Q

what is the formula of speed of wave

A

v= f lambda

50
Q

what is the formula for deep and shallow region for refraction of waves

A

v/lambda = v/lambda

51
Q

what does diffraction of waves mean

A

is the spreading of waves when the waves propagate through a slit or side of a barrier.

52
Q

what changes to the wave will occur when diffraction occur

A

amplitude, direction of propagation

53
Q

what happens to the amplitude when diffraction of waves occur

A

decreased, wave energy diverges and spread out to a wider region

54
Q

what happens to the direction of propagation when diffraction of waves occur

A

from one direction to many, wavefront spreads

55
Q

draw the pattern of diffraction for wide slit

A

aa

56
Q

draw the pattern of diffraction for narrow slit

A

aa

57
Q

draw the pattern of diffraction for short wavelength

A

aa

58
Q

draw the pattern of diffraction for long wavelength

A

aa

59
Q

what is diffraction of waves influenced by?

A

size of slit and wavelength

60
Q

give 3 examples for the diffraction of waves in daily life

A

water waves,
diffraction of water waves produces calm of water regions suitable for docking of ships and water recreational activities.

light waves,
holograms produced by effects of diffraction of light are used as safety features on bank cards such as debit cards and credit cards.

sound waves
infrasonic waves produced by elephants have long wavelength to facilitate ling distance communication between elephants

61
Q

what is the meaning of interference of waves

A

is the superposition of two or more waves from a coherent source of waves

62
Q

how are two waves coherent

A

when the frequency of both waves is the same and the phase difference is constant.

63
Q

what does superposition of waves produces

A

constructive interference

destructive interference

64
Q

how does constructive interference occurs

A

when two crests are in superposition

when two troughs are in superposition

65
Q

how does destructive interference occur

A

when a crest and a trough are in superposition to produce zero combined displacement

66
Q

how do you identify constructive interference in ripple tank

A

bright and dark area

67
Q

how do you identify destructive interference in ripple tank

A

grey area

68
Q

how do you identify constructive and destructive interference in interference of light waves

A

constructive interference produce bright fringe while destructive interference produce dark fringe

69
Q

how do you identify constructive and destructive interference in interference of sound waves

A

loud sound = constructive interference

soft sound = destructive interference

70
Q

identify destructive and constructive interference from sketch

A

aaa

71
Q

what is the formula for interference of waves

A

lambda = ax/D

72
Q

give 3 examples for applications of interference of waves in daily life

A

bulbous bow
coating on the surface of anti-reflection lens
microphone and transmitter system

73
Q

HISTORY OF ELECTROMAGNETIC WAVES

what did thomas young discovered in 1801

A

light is a wave through experiments on interference of light

74
Q

HISTORY OF ELECTROMAGNETIC WAVES

what did james maxwell discovered in 1862

A

put forth the theory that light is an electromagnetic wave.

75
Q

HISTORY OF ELECTROMAGNETIC WAVES

what did heinrich hertz discovered in 1887

A

generated a different kind of electromagnetic wave, that is radio wave

76
Q

HISTORY OF ELECTROMAGNETIC WAVES

what did is the discovered in early 20th century

A

electromagnetic waves are made up of:

  1. gamma ray
  2. x-ray
  3. ultraviolet ray
  4. visible light
  5. infrared ray
  6. microwave
  7. radiowave
77
Q

what are electromagnetic waves made up of

A

electric field and magnetic field that oscillate perpendicularly to one another

78
Q

draw the electromagnetic spectrum that shows the frequency and wavelength of rays

A

aaa

79
Q

how is radio wave used

A

long distance radio communication
local radio and tv broadcasting
wireless communication
millimetre-wave machine to scan body of passengers at airport

80
Q

how is microwave wave used

A

international communication through use of satellite
mobile phone framework
communication between electronic devices: wifi, bluetooth,
detection of plane radar and speed trap
cooking

81
Q

how is infrared ray used

A

enable living things to see
photography
photosynthesis in green plants
laser light used in cutting of metal, measurement of land and sending of information through optical fibres.

82
Q

how is ultraviolet ray used

A

harden tooth filling material
determines authenticity of currency notes
treatment of jaundice in babies
purification of drinking water
sterilising surgical instruments and food
insect traps

83
Q

how is x-ray used

A

detects fractures or broken bones and examines internal organs
checking of welding connections
baggage scanning at airport
determine authenticity of paintings

84
Q

how is gamma ray used

A

kills cancer cells in radiotherapy
sterilisation of surgical and medical equipment is bulk
used in food processing industry so that food can last longer

Physics (2 decks)

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