Waves and sounds Flashcards
1
Q
waves in hearing
A
longitudinal (make long distance calls)
2
Q
Waves in light
A
transverse waves
3
Q
sound waves
A
need a medium to travel through since it is a change in pressure from high to low
4
Q
light waves
A
do not need a medium since they transfer energy through alternating electric and magnetic fields
5
Q
mechanical waves
A
obey the laws of classical mechanics and require a medium
6
Q
electromagnetic waves
A
do not need a medium to travel through
7
Q
wavelength
A
is the distance from any point in the wave to the point where the wave begins to repeat itself
8
Q
frequency
A
is the number of wavelengths that pass a fixed point in one second
9
Q
period
A
is the time it takes the wave to travel the distance of one wavelength and is the reciprocal of frequency
10
Q
frequency does not change when
A
you move from one medium to another and neither does the period
11
Q
what changes when a wave travels through another medium
A
the velocity changes
12
Q
what happens to a sound wave when temperature increases in a gas
A
sounds waves will move more quickly
13
Q
Why do sound waves travel faster in water than air
A
water has a much higher bulk modulus
14
Q
amplitude of a wave
A
can be measured as the distance between the x-axis and either the top of a crest or the bottom of a trough
15
Q
what happens to amplitude when a wave moves from one medium to another
A
amplitude changes
16
Q
pitch
A
a measure of how high or low a note sounds, correlates with frequency
17
Q
intensity
A
is the power level of a sound wave.
18
Q
in decibels if you increase by 100 you add
A
10
19
Q
when a wave reflects off a medium that is more dense
A
it is inverted
20
Q
when a wave reflects off a medium less dense it is
A
it is reflected upright
21
Q
audible frequency for humans
A
20 to 20,000Hz
22
Q
waves above the frequency for humans
A
ultrasonic
23
Q
for an ultrasound machine the greater the difference in density
A
the greater the intensity of reflected sound
24
Q
point created by maximum destructive interference is called
A
node
25
two vertical lines experience maximum constructive interference
antinode
26
attenuation
the decrease in the intensity of a wave propagating through a medium
27
when a wave attenuates what decreases
its intensity
28
doppler effect
is the change in the observed frequency when a wave source or observe moves towards or away from each other
29
when the source or the observer is moving toward each other
the observed frequency is higher
30
as distance decreases so does the
time interval between wave fronts
31
what does the wavelength for light do when the source and observer are approaching each other
creates a blue shift
32
when objects are moving in the same direction at the same speed
there is no doppler effect
33
shock waves
is a conical wave front produced when the velocity of the sound source exceeds the velocity of the sound wave
34
pressures differences in a shock wave are
so different that it causes the observer to perceive it as a boom
35
amplitude of a standing wave is
constant
36
Intensity and amplitude related
I= A^2
37
30 db to 10 db is a
100 fold decrease
38
light acts like both
a wave and a particle
39
emission of light occurs when
the light emitted transitions from higher to lower energy states
40
light emitted by electrons is in the form of
photons
41
the dominant frequency of emitted light is
directly proportional to the temperature
42
black is the absorption of
all light
43
white is the reflection of
all visible light
44
when light is polarized
its electric and magnetic fields are oriented in a particular rather than a random way
45
if light oscillates parallel to the y-axis
it is said to be vertically polarized
46
if light oscillates parallel to the x-axis
it is said to be horizontally polarized
47
magnetic fields oscillate in planes perpendicular to the
planes in which electric fields oscillate
48
source of light is
a vibrating charge
49
light is said to be circularly polarized when it consists of electric fields of
constant magnitude that change direction in a rotary manner
50
reflection is
light bouncing off the boundary between media
51
Refraction
is light bending as it passes into a new medium
52
Dispersion
is a type of refraction is the splitting of light according to frequency
53
Diffraction is
the spreading of light when it encounters an edge
54
The angle at which a wave strikes an interface is called
the angle of incidence
55
the angle at which a wave is reflected is called
the angle of reflection
56
the angle of incidence is equal to the angle of reflection when light
reflects off a flat surface
57
what do all waves do
refract
58
the greater index of refraction results in
the more slowly light moves through the medium
59
indice of refraction for water
1.3
60
indice of refraction for glass
1.5
61
when light approaches a medium with a higher index of refraction at an angle other than 90 degrees
one part of the wave front changes speed before the other and the light ray remains perpendicular to the wave fronts
62
when light enters a new medium what remains the same and what changes
the frequency remains the same while the wavelength and velocity change
63
refraction does not change the
phase of the wave at the interface between two media
64
if the medium's index of refraction is higher
the wavelength becomes shorter
65
if the index of refraction is lower
the wavelength becomes longer
66
when light is coming from a higher index of refraction the angle of incidence can be so great to cause
total internal reflection
67
if the angle of incidence is large enough
all photons will be reflected at the angle of reflection and none will refract. angle called critical angle
68
critical angle equation
theta critical= sin inverse (n2/n1)
69
dispersion
is the separation of light into different frequencies due to their different indices of refraction in a medium
70
chromatic dispersion
has light refracted at its different frequencies resulting in different velocities and wavelengths
71
diffraction is
the spreading of light that occurs when a wave bends around the edges of an object or opening
72
longer wavelengths will do what compared to shorter wavelengths
defract more
73
the fact that a wave can be reflected supports both
the particle theory of light and the wave theory
74
the difference between lens and mirrors with interaction with light
light reflects when it encounters a mirror and refracts when it encounters a lens
75
thin lens
is a lens whose maximal thickness is small relative to the radius of curvature, object distance, and image distance
76
focal point
the point at which parallel light rays converge or appear to converge after reflecting off of the mirror or passing through the lens
77
real focal point
where light rays actually converge
78
virtual focal point
is a point at which light only appears to converge
79
focal point for a concave mirror
lies in front of the mirror
80
focal point for a convex mirror
is located behind the mirror
81
focal length
is the distance between a mirror and its focal point. It is equal to half the radius of curvature f=R/2
82
power of a lens is determined by
P=1/f
83
lens have two
focal points
84
what is the power of a lens measured in
diopters (m^-1) must convert into meters to calculate
85
converging mirror
reflects light rays such that they converge at a point in front of the mirror. The point at which reflected rays converge is the focal point
86
Converging lens
light converges behind where the light source is
87
converging mirror
concave
88
converging lens
convex
89
what makes a spherical mirror reflect light at one point
if the radius of curvature is large and the angles of incidence are relatively small
90
how does a diverging mirror reflect light
reflects light rays such that the observer perceives them as converging at a point on the opposite side of the mirror from the observer
91
diverging lens
refracts light rays such that they appear to converge at a point on the same side of the lens as the light source, opposite the side of the observer
92
diverging mirror is a
convex mirror
93
diverging lens is a
concave lens
94
if the center of a lens is thicker than its ends
it will converge light regardless of its shape or which direction light moves through the lens
95
real, inverted image
on the same side of the mirror or lens as the observer and positive
96
virtual, upright
on the opposite side of the mirror or lens from the observer and negative
97
positive and negative are dictated by
positive on the same as the observer and negative on the opposite side of the observer
98
diverging lens and mirrors always produce
virtual upright images
99
what is unique about convergers
they can make both real,inverted images and virtual upright images
100
when the object is located beyond the focal point
convergers will always produce a real inverted image located on the side of the observer
101
if the object is placed within the focal length the image formed will be (convergers)
virtual and upright
102
real image is always located
on the same side as the observer
103
focal distance for a converging mirror and lens
positive
104
focal distance for a diverging mirror and lens
negative
105
object distances are given a positive sign when
objects are where they belong. objects belong on the same side as the observer for mirrors and on the opposite side from an observer for lenses
106
magnification
-di/do
107
diverging lens and mirrors always form images that are
smaller in size than the objects they represent
108
plane mirrors
the image formed by a plane mirror is the same distance from the mirror as the object
109
chromatic abberation
arise when light of higher frequencies focuses closer to a lens than does light of lower frequencies
110
chromatic abberations only occur when
different frequencies of light pass through a lens simultaneously
111
spherical abberations
when rays farther from the center of a lens focus at different points than do rays closer to the center of the lens
112
the lateral magnification of a two lens system is the product of
the lateral magnifications of each lens M=m1*m2
113
Two lenses in contact with each other have an effective power equal to the sum of their individual powers
Peff=P1+P2
114
increase bending of light would increase
the lens power
