Physics 106 Exam 3

Front 1

Light has characteristics of what?

Back 1

an electromagnetic wave and a particle

Front 2

How tall must a flat mirror hanging on the wall be in order for a person to see their feet and the top of their head at the same time?

Back 2

Half the Height of the Person

Front 3

What would you see if a small mirror were hung at your belt level?

Back 3

Your knees

Front 4

An observer facing a mirror observers a light source that is in front of the mirror. Where does the observer percieve the light source to originate from

Back 4

The same place and distance behind the mirror as the real source is infront of the mirror. (it is therefore a virtual image)

Front 5

What is a virtual image?

Back 5

The light does not actually come from that point—it only looks like it does. You have to look into the mirror or lens to see it.

Front 6

What does Snell's law describe?

Back 6

Refraction

Front 7

The speed of light in glass is _______the speed of light in air?

Back 7

Less than
think of the relationship between speed of light and velocity and wavelength
C=LV (L is lambda)

Front 8

Light passes through three materials N1=1, N2=1.3 and N3=1.5. Each change in N makes the light refract. Will the angle with the normal at N3 be different if light only goes from N1 to N3 than if it had gone from N1 to N2 to N3?

Back 8

No. The angle to the normal will be the same regardless of N2 being present

Front 9

An observer looks directly down on a fish swimming below the surface. How deep does the fish appear to be in relation to its actual depth?

Back 9

It appears to be shallower

Front 10

A fish swims below the surface of the water. An observer looking from a distance looks ________ to the fish.

Back 10

Taller than he really is

Front 11

A fish is 1.2 m beneath the surface of a still pond of water. At what maximum angle can the fish look toward the surface (measured with respect to the normal to the surface) in order to see a fisherman sitting on a distant bank? (for water, n = 1.333) A drawing might help. Take the fishes perspective.

Back 11

48.6
n1*sinθ=n2*sinθ
1sin90=1.33sinθ

Front 12

To be a real image the light has to _________?
If you put up a screen _______?

Back 12

actually pass through the image point.
I can see an image on it.

Front 13

to be a virtual image ___________?
Where do you have to look to see the image?

Back 13

The light does not actually come from that point—it only looks like it does.
- into the mirror to see it.

Front 14

When we look into the water at a fish is the fish virtual, real, upright, or inverted?

Back 14

Virtual and upright

Front 15

Light from an object reflected by a mirror in such a way that the rays diverge after reflection as if they were coming from a point behind the mirror produces what kind of image?

Back 15

Virtual

Front 16

Which of the following is not a principal ray of a concave mirror?
a. a ray that goes through the center of the curvature of the mirror
b. a ray that approaches the mirror along a line parallel to the axis
c. a ray that goes through the focal point on the way to the mirror
d. all three are used

Back 16

D. All three are used

Front 17

Which 2 of the following best describes the image of a concave mirror when the object is far away from the mirror (object distance is >C)? real, virtual, upright, inverted

Back 17

Real and Inverted

Front 18

Which of the following best describes the image of a concave mirror when the object is at a distance smaller than the focal point distance from the mirror? real, virtual, upright, inverted

Back 18

Virtual and upright

Front 19

Which of the following best describes the image of a concave mirror when the object is at a distance between the center of curvature and the focal point distance from the mirror? real, virtual, upright, inverted

Back 19

Real and Inverted

Front 20

Which of the following is not a principal ray of a converging lens?
A ray that goes through the center of the curvature of the lens
A ray that approaches the lens along a line parallel to the axis
A ray that goes through the focal point on the way to the lens
All three are used

Back 20

A ray that goes through the center of curvature.

In a lens the third ray is drawn through the center of the lens

Front 21

Which of the following describes the image for a thin converging lens that forms whenever the magnitude of the object distance is greater than that of the lens' focal length? Real, upright, inverted, virtual

Back 21

Real and inverted

Front 22

A lens is used to image an object onto a screen. If the right half of the lens is covered, what happens to the image?

Back 22

the image becomes fainter. the right half of the lens is covered not the right half of the object, so half the light rays project on the screen making it dimmer

Front 23

A lens is used to image an object onto a screen. If the right half of the object is covered, what happens to the image?

Back 23

The left half of the image disappears

Front 24

What happens to the image for a thin converging lens if the object is moved closer to the lens so that it is closer to the lens than the focal point?
Real, upright, inverted, virtual

Back 24

Virtual and upright

Front 25

Interference occurs with which of the following?
Light waves
Sound waves
Water waves
All of the above

Back 25

All of the above

Front 26

Phase differences between the portions of the wave are caused by?

Back 26

Differences in the distance traveled, and phase changes occuring on reflection

Front 27

For shorter steps (shorter wavelength) the minimums and maximums__________

Back 27

Get closer together

Front 28

When the slits get closer together the minimums and maximums . . .

Back 28

get further apart

Front 29

When light hits a mirror and bounces off there is a _________ phase shift

Back 29

180 degree

Front 30

When light reflects off a medium with a larger n there is a 180o phase shift.
When light reflects off a medium with a smaller n there is no phase shift

Back 30

Yep thats true

Front 31

An interference pattern is formed on a screen by shining a planar wave on a double-slit arrangement. If we cover one slit with a glass plate, the phases of the two emerging waves will be different because the wavelength is shorter in glass than in air. If the phase difference is 180°, how is the interference pattern altered?

Back 31

the bright and dark spots are interchanged

Front 32

Two identical slides in air are illuminated with monochromatic light. The slides are exactly parallel and the top slide is moving slowly upward. Assume that only the top surfaces are reflective. What do you see in top view?

Back 32

Sequentially all black, then all bright

Front 33

An oil film on water reflects different colors more or less brightly owing to interference, depending on the film thickness. In an outer region where the film is thinnest (thin compared to visible wavelengths), all colors reflect brightly. From this information, we can tell that the index of refraction of the oil is______than that of water

Back 33

Less

Front 34

What happens to the color seen as the soap film gets thicker?

Back 34

the color changes from green to yellow
(goes to a longer wavelength)
ROYGBIV

Front 35

What is the minimum thickness of a glycerin film (n=1.47) on which light of wavelength 600 nm shines that results in constructive interference of the reflected light? Assume the film is surrounded front and back by air.

Back 35

102nm
2nt=ml (l=lamda) and
d=2t because we want constuctive interference
2(1.47)(2t)=600nm
600/4(1.47)=t
t=102nm

Front 36

When a ray of light is incident on two polarizers with their polarization axes perpendicular, no light is transmitted. If a third polarizer is inserted between these two with its polarization axis at 45° to that of the other two, does any light get through to point P

Back 36

yes.

Front 37

Look at the equations for double slit and single slit

Back 37

Double
dsinθ(bright)=ml
dsinθ(dark)=(m+1/2)l
Single
dsinθ(dark)=m(l/a)

Front 38

If I am nearsighted what kind of lenses do I need?

Back 38

Diverging

the image is formed infront of where it needs to be...diverging lenses move this image further back in the eye to the right spot

Front 39

If I am farsighted whatkind of lenses do i need?

Back 39

Converging...need to form the image closer than it is naturally

Front 40

For a simple magnifying glass the image is???

Back 40

Virtual

Front 41

For a telescope we get a_________ image?

Back 41

virtual de-magnified

Front 42

A 1 cm tall object is placed 4 cm to the left of a converging lens of focal length 8 cm. A diverging lens of focal length -16 cm is 6 cm to the right of the converging lens. Find the position and height of the final image. The image is

Back 42

Upright and Virtual

Front 43

Can you get a real image from a divergin lens?

Back 43

Yes, but only if you create a negative object, which would be the image of another lens.