Waves Flashcards
1
Q
Wave speed?
A
v = lamba. f
2
Q
Angular frequency?
A
w = 2pif
3
Q
Speed of sound?
A
v = squaroot ( B/density)
B= bulk modulus
4
Q
Doppler effect?
A
f’ = f . (v +/- vd) / (v -/+ vs)
5
Q
Intensity of sound? Unit?
A
I = P(ower)/A
in Watt/m^2
6
Q
Sound level?
A
decibel = 10 log (Io/I)
7
Q
Change in sound level?
A
Decibel f = decibel i + 10 . log (If/Ii)
8
Q
Range of radio waves?
A
10^9 - 1 m
9
Q
Range of microwaves?
A
1m - 1 mm
10
Q
Range of infrared?
A
1 mm - 700 nm
11
Q
Range of visible light?
A
400 - 700 nm
12
Q
Range of UV?
A
400 - 50 nm
13
Q
Range of x-rays?
A
50 - 10^-2 nm
14
Q
Range of gamma rays?
A
less than 10^-2 nm
15
Q
What is the law of reflection?
A
theta 1 = theta 2
16
Q
What is the optics equation?
A
1/f = 1/i + 1/o = 2/r
17
Q
What is magnification equal to?
A
m = -i / o
18
Q
What is the index of refraction equal to?
A
n = c/v
19
Q
How does the light bend when n2>n1
A
Light bends toward the normal
20
Q
How does the light bend when n2
A
Light bends away from the normal
21
Q
What is the equation for Snell’s law?
A
n1 . sin theta 1 = n2 . sin theta 2
22
Q
What is the equation for the critical angle?
A
theta c = sin -1 (n2/n1)
23
Q
What does the critical angle represent?
A
The minimum incident angle at which total internal reflection occurs
24
Q
When should the lensmaker equation be used? What is it?
A
When the thickness of the lens is NOT negligible
1/f = (n-1) x (1/r1 - 1/r2)
25
What is the order of colors in the visible spectrum and their wavelengths?
```
Red: 620-750
Orange: 590-620
Yellow: 570-590
Green: 490-570
Blue: 450-490
Violet: 380-450
```
26
What does m (-) mean?
Inverted image
27
What does m (+) mean?
Upright image
28
What does |m|>1 mean?
Magnified image
29
What does m = 1 mean?
Same size image
30
What does |m| inferior to 1 mean?
Reduced image
31
What is the image when the object is placed between F and C of a concave mirror?
Real, inverted, magnified
32
What is the image when the object is placed at F of a concave mirror?
No image
33
What is the image when the object is placed between F and concave mirror?
Virtual, upright, magnified
34
What does a r>0 mean for a mirror?
Concave = converging
35
What does i>0 mean for a mirror and lens?
Real image
36
What does o>0 mean for a mirror?
Object is in front of the mirror
37
What does r
Convex = diverging
38
What does i negative mean?
Virtual image
39
What is the power of a lens equal to? What is the unit?
1/f (focal length)
| Diopters
40
What image will be produced by a convex mirror?
Virtual, upright, reduced
41
How does the "real" side compare between mirrors and lenses?
Real side mirror = in front of mirror
| Real side lenses = opposite side from light source
42
What does f (-) mean for a lens
Concave = diverging
43
What does f>0 mean for a mirror?
Concave = converging
44
What does f (-) mean for a mirror?
Convex = diverging
45
What does f>0 mean for a lens?
Convex = converging
46
What does r (-) mean for a lens?
Concave = diverging
47
What does r>0 mean for a lens?
Convex = converging
48
What is the power of the eye equal to?
60 diopters
49
How to calculate the focal length of a multiple lens system?
1/f = 1/f1 + 1/f2
50
How to calculate the power of a multiple lens system?
P = P1 + P2
51
How to calculate the magnification of a multiple lens system?
m = m1 x m2
52
How to calculate the positions of dark fringes in a single slit-lens setup?
a x sin theta = n x lamba
a = width of slit
theta = angle between line from center of slit and fringe
n = number of the fringe
53
How to calculate the positions of dark fringes in a double slit-lens setup?
d x sin theta = (n + 0.5) x lamba
d = distance between slits
theta = angle between line from center of slit and fringe
n = number of the fringe
54
What are the minima?
Dark fringes
55
What are the maxima?
Light fringes
56
Does plane polarization affect? What does it not?
Amount of light passing through a medium = its intensity
| Does not affect wavelength, frequency, or speed
57
What does refraction affect? What does it not?
Wavelength
| Does not affect frequency or amplitude
58
How does conjugation affect the color of the UV light absorbed?
Higher degree of conjugation = higher wavelength light absorbed = lower energy color observed
59
How can one increase the angle/degree of diffraction?
Decrease the slit width
| Increase the wavelength
60
Are sound waves longitudinal or transverse?
Longitudinal
61
What types of waves are transverse?
Electromagnetic
62
Assuming the distance o is positive, what can be said of inverted and upright images?
Inverted images are real
| Upright images are virtual
63
What is farsightedness?
Hyperopia
64
What is nearsightedness?
Myopia
65
What is the speed of sound in air?
340 m/s
66
What is the speed of light in air?
3 x 10^8 m/s
67
What is the range of audible frequencies?
20 = 20,000 Hz
68
Which type of hearing declines with age?
High frequency hearing
69
What does it mean when f = f'?
The detector and source are moving in same direction and at same speed
70
What is the intensity of the threshold of hearing?
Io = 1 x 10^-12 W/m^2
71
What are the two measures that intensity of sound is related to?
1. Amplitude^2
| 2. 1/d^2 (distance to source)
72
What is the wavelength of a wave in a string or pipe open at both ends?
lambda = 2L/n
n = number of antinodes = top of the wave
73
What is the frequency of a wave in a string or pipe open at both ends?
f = n.v / 2L
n = number of antinodes
74
What is the wavelength of a wave in a closed pipe?
lambda = 4L/n
n = number of quarter wavelengths
75
What is the frequency of a wave in a closed pipe?
f = n.v / 4L
n = number of quarter wavelengths
76
What does it mean when an object shatters at a certain frequency?
that frequency is very close to the object’s natural frequency
77
What is damping?
Think of someone on a swing starting at full height. If they keep swinging without putting effort in, they will eventually come to a stop.
78
What is the difference between how a lens and how a mirror refract light?
Lenses refract light at an angle that depends on its wavelength VS mirrors reflect light of all wavelengths at the same angle
79
What does the distance from the center of the lens of the eye to the retina represent?
Always the image distance
80
How does the focal length of the eye change?
Depending on the object distance: the closest to the eye, the smaller the focal length --> The ciliary muscles contract
81
What images are produced by convex lenses (2 types)? Who needs them? Which is most common?
When O is further than F: Real inverted images (more common)
When O is between F and lens: Virtual upright
Farsighted
82
What images are produced by concave lenses? Who needs them?
Virtual upright
| Nearsighted
83
How does an increase in temp affect the speed of sound?
Increase in temp = decrease in speed
84
What does it mean when the image of convex lens is in front of the lens?
It is virtual --> i is negative
85
What is the focal length of the relaxed eye? Why?
i, because the object is very far
86
What is the lens of the eye: concave or convex? What type of images does it produce?
When O is further than F: Real inverted images (more common)
| When O is between F and lens: Virtual upright
87
Does a magnifying glass work underwater? Why?
No, because the angle will be closer to the normal
88
Would an increase in the index of refraction increase the power of a lens? Why?
Yes, because it would increase the bending of light rays
89
Would increasing r increase the power of a lens? Why?
No, because it would flatten the lens and reduce the degree to which light is bent
90
Which type of lenses can create real inverted images?
Convex ONLY!
91
What happens when you place an object at the focal point of a lens?
No image is formed, same as mirrors
92
What does an inverted image look like?
Inverted up and down, and left and right
93
What happens to the light wave during magnification?
Light reflects off the the object and refracts through the lens
94
When do light waves diffract?
When they encounter obstacles or apertures
95
When do light waves refract?
When they transition from one medium to another
96
What happens when a frequency is moving toward you?
It's getting higher
97
What happens when a frequency is moving away from you?
It's getting lower
