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Biophysics > Waves > Flashcards

Waves Flashcards

1
Q

are typically disturbances in some medium

A

waves

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2
Q

electromagnetic waves include

A

light or radio waves

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3
Q

movement of gas molecules

A

sound waves

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4
Q

movement in solids

A

seismic waves

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5
Q

occurs whenever a system is disturbed from equilibrium due to transfer of energy and when the disturbance can travel or propagate from one region of the system to another.

A

waves

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6
Q

aves can show a visible disturbance or oscillation in the medium in which they occur; however, waves do not move ____, they only transfer ____.

A

matter
energy

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7
Q

a vibration or a disturbance in space.

A

wave

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8
Q

a wave can be:

A

mechanical wave
electromagnetic wave

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9
Q

wave that requires a medium

A

mechanical waves

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10
Q

wave that does not require a medium

A

electromagnetic waves

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11
Q

two types of mechnical waves

A

transverse wave
longitudinal wave

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12
Q

cause the medium to move perpendicular to the direction of the wave.

A

transverse wave

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13
Q

waves cause the medium to move parallel to the direction of the wave.

A

longitudinal

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14
Q

example of electromagnetic waves

A

light
microwave
infrared
x-rays
UV rays
radiowaves

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15
Q

requires a medium to transfer energy from one location to another.

A

mechanical wave

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16
Q

example of mechanical wave

A

sound waves
ocean waves
ripples in water
earthquake

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17
Q

is the substance through which a wave can travel

A

medium

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18
Q

example of medium

A

air
water
strings
solids
liquids
gases

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19
Q

As the wave moves through the medium, its ____will oscillate back and forth, but do not actually move with the wave.

A

particles

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20
Q

types of mechanical waves

A

transverse wave
longitudinal wave

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21
Q

energy moves up and down or side to side while traveling forward

A

transverse wave

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22
Q

study the parts of transverse wave

A

+

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23
Q

energy moves along the medium while traveling forward.

A

longitudinal wave

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24
Q

parts of a longiudinal wave

A

+1

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25
Q

particles are closed together.

A

compression

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26
Q
  • particles are spread apart.
A

rarefaction

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27
Q
  • it does not require any material medium for its propagation and can travel even through a vacuum; caused by varying electric and magnetic fields.
A

electromagnetic waves

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28
Q

wave behavior (4)

A

reflection
refraction
diffraction
interference

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29
Q

wavelength from longest to shortest

A

radio (10^3)
microwave (10^-2)
infrared (10^-5)
visible (0.5x10^-6)
ultraviolet (10^-8)
x-ray (10^-10)
gamma ray (10^-12)

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30
Q

wavelength of radio waves

A

10^3

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31
Q

wavelength of microwave

A

10^-2

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32
Q

wavelength of infrared

A

(10^-5)

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33
Q

wavelength of visible light

A

0.5x10^-6

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34
Q

wavelength of ultraviolet light

A

10^-8

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35
Q

wavelength of xray

A

10^-10

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36
Q

wavelength of gamma ray

A

10^-12

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37
Q

_____ wavelength, ____ frequency

A

decreasing
increasing

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38
Q

the distance between one point on a wave and the exact same place on the next wave

A

wavelength

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39
Q

It is the wave motion in one period and is often measured from crest to crest along a wave or from trough to trough along a wave

A

wavelength

40
Q

indicates how many waves go past a point in one second; unit of measurement is hertz (Hz).

A

frequency

41
Q

frequency’s unit of measurement is ____

A

hertz (Hz)

42
Q

the higher the _____, the more energy in the wave

A

frequency

43
Q

is the reciprocal of of frequency, measured in seconds.

A

period (T)

44
Q

period is measured in

A

seconds

45
Q

relationship of frequency and period

A

T = 1/f

46
Q

maximum displacement of vibrating particles of the medium from their equilibrium positions.

A

amplitude

47
Q

distance travelled by a wave crest in one period

A

wave velocity

48
Q

It depends on the medium in which the wave is traveling. It varies in solids, liquids and gases.

A

wave velocity

49
Q

wave velocity formula

A

v = λf or v = λ/T

where v - wave veloicty
λ - wavelength
F - frequency
T - period

50
Q

λ stands for

A

wavelength

51
Q

F stands for

A

frequency

52
Q

T stands for

A

period

53
Q

An observer sitting on a shore counts the waves and finds that there are 6 waves per minute hitting the shore. She measures the distance between consecutive crests to be 10 m. What is the velocity of the waves?

A

f = 6 waves/min * 1 min/60s = 0.10 wave/s

v =λf = 10 m x 0.10/s = 1.0 m/s

54
Q

Medical ultrasound waves travel at about 1500 m/s in soft tissue. Higher frequencies provide clearer images but don’t penetrate to deeper organs.

     Find the wavelengths of (a) 8.0 -MHz ultrasound used in fetal imaging and (b) 3.5 -MHz ultrasound used to image adult’s kidneys. Express your

     answers in mm.
A

a = λ = v/f = 1500 m/s / 8.0x10^6 /s = 1.88 x10^-4 m x 1000/1 = 0.188m

b= λ = v/f = 1500 m/s / 3.5x10^6/s = 4.29 x10^-4 m x 1000 mm/1m = 0.429 mm

55
Q

If a wave is to travel through a medium such as water, air, steel or a stretched string, it must cause the particles of that medium to oscillate as it passes, which requires both ___(for kinetic energy) and ____( for potential energy)

A

mass
elasticity

56
Q

the velocity of the wave in a string/cord is determined by

A

√ elastic property/ inertial property

57
Q

elastic property is

A

tension (F)

58
Q

inertial property is

A

mass density/mass per unit length

59
Q

the bouncing back of a wave as it meets a surface or boundary

A

reflection

60
Q

can all types of wave be reflected?

A

yes

61
Q

The angle of incidence (Ɵi) is equal to the angle of the reflected wave (Ɵr)”

A

law of reflection

62
Q

an imaginary line that is perpendicular to the surface

A

normal

63
Q

-how much of the wave that is reflected depends on the impedance between the two mediums.

A

normal and surface

64
Q

describes the difference in densities of the two mediums, the greater the difference in mediums, the greater the

                               .
A

impedance

65
Q

he greater the difference in mediums, the greater the
.

A

impedance

66
Q

-As the impedance increases, more of the wave’s energy is ___instead of being transmitted into the next medium.

A

reflected

67
Q

occurs when a wave bends as it moves from one substance into another.

A

refraction

68
Q

___ waves may change speed and wavelength but do not change frequency

A

refracted

69
Q

refracted waves may change ___ and ___ but do not change frequency

A

speed
wavelength

70
Q

the bending of a wave around the edges of an opening or an obstacle.

A

diffraction

71
Q

a wide gap will have a __ diffraction effect

A

small

72
Q

a narrow gap will have a ___ diffraction effect

A

large

73
Q

a large wavelength will have a ___ diffraction

A

large

74
Q
  • the phenomenon that occurs when two waves meet while traveling at the same medium; two or more waves combine to form a new wave
A

interference

75
Q

occurs when the wave amplitudes reinforce each other, building a wave of even greater amplitude

A

constructive interference

76
Q

occurs when the wave amplitudes oppose each other resulting in waves of reduced amplitude

A

destructive inference

77
Q

“When 2 waves meet while traveling through a medium at the same time, the result is a wave whose displacement is equal to

A

the vector sum of the displacement of the two waves”

78
Q

are the result of the interference of two identical waves with the same frequency a nd the same amplitude traveling in opposite direction.

A

standing waves

79
Q

point on standing wave that always undergo complete destructive interference and with zero amplitude

A

node

80
Q

point halfway between two nodes at which maximum amplitude occurs

A

antinode

81
Q

has the lowest frequency and longest wavelength

A

first harmonic standing wave

82
Q

It consists of a node at both ends and one antinode between them

A

fundamental frequency (first harmonic) standing wave

83
Q

L in a standing wave refers to the

A

1/2 of wavelength λ

84
Q

thus λ = ___ L

A

2

85
Q

frequency when L is given

A

v / 2L

86
Q

fn formula

A

fn = n/2 v/L

87
Q

All mechanical waves are capable of transporting ____ when they propagate through a medium

A

energy

88
Q

the energy is carried out by ___ motion of the molecules that composes the medium

A

vibrational motion

89
Q

the energy transported by wave is prportional to the square of the ____and to the square of the ___

A

frequency
amplitude

90
Q

formula for power

A

p = x^2 (Where x is amplitude)

91
Q

on a calm day, the waves reaching a beach have an amplitude of 0.1 m. On a much windier day, the amplitude is 0.5m, although the speed and wavelength of the waves is the same. What is the ratio of the power delivered by the waves on the windy day compared to that on a calm day?

A

25

92
Q

velocity formula based on elasticity and inertial property

A

v = √F /µ

93
Q

a flexible cable, 30m long and weighing 70 N, is stretched between two poles by a force of 2.0 kN, if the cable is struck sideways at one end, how long will it take the transverse wave to travel to the other end and return?

A

v = 91.67 m/s
tT = 0.65s

94
Q

the time required for a wave to complete one full cycle is called the wave’s ___

A

period

95
Q

if the amplitude of a wave traveliongin a rope is doubled, the speed of the wave of the rope will decrease

A

false

Biophysics (25 decks)

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