Clicker Questions for NEXUS/Physics

Light: Wave model

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What do we expect from our light and shadow analysis?

1. Two sharp bright spots

2. Two blurry bright spots

3. One wide blurry bright spot

4. One wide sharp bright spot

5. Something else

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When we put light through a thin pair of slits, we get a pattern different than we would expect from our light and shadow ray-model analysis. The two slit pattern looks like this.

What will happen if we close one of the slits?

A. The pattern will get dimmer but not change shape.

B. The pattern will become one spot, like in the ray model.

C. We still have stripes but different ones.

D. Something else.

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It’s a crest (max) now…what about 2 seconds from now?

A. It will be a crest (max)

B. It will be a trough (min)

C. It will be zero

D. Other

Say T = 4 sec

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It’s a zeronow…what about 2 seconds from now?

A. It will be a crest (max)

B. It will be a trough (min)

C. It will be zero

D. Other

Say T = 4 sec

Below is shown a “ripple” picture showing crests and troughs of the ripples of water coming from two slits in a mask at a particular instant. Crests are solid lines, troughs are dashed. The small star represents a cork. The cork will move:

1. Not at all.

2. Outward away from the slits

3. Up and down the same as with one source

4. Up and down twice as high as with one source

5. Up and down half as high as with one source

★

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Below is shown a “ripple” picture showing crests and troughs of the ripples of water coming from two slits in a mask at a particular instant. Crests are solid lines, troughs are dashed. The small star represents a cork. The cork will move:

1. Not at all.

2. Outward away from the slits

3. Up and down the same as with one source

4. Up and down twice as high as with one source

5. Up and down half as high as with one source

★

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A long straight jetty has had two holes broken into it by a storm. A series of wavefronts strike it giving rise to outgoing circular waves . A fisherman watching various boats for a while after this picture was taken notices that some of the boats oscillate up and down a lot as the waves pass them and some oscillate almost not at all. Rank order these boats by how much they oscillate

1. A > D > B > C2. A > B > D > C3. A = C > B > D4. A = C > B = D5. A = C > D > B = 06. C > A > B > D = 07. Other

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path A

path B

point X (on screen)

Following along path A at a fixed instant of time

Following along path B at an instant of time

starting from top slit

starting from bottom slitpoint X

Is the result 1. a maximum,2. a minimum, 3. Zero or 4. neither?

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path A

path B

point Y (on screen)

Following along path A at a fixed instant of time

Following along path B at an instant of time

starting from top slit

starting from bottom slitpoint Y

Is the result 1. a maximum,2. a minimum, 3. Zero or 4. neither?

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path A

path B

Point X (on screen)

At a LATER TIME after the time shown below

starting from top slit

starting from bottom slitPoint X

At X the wave1. has a steady maximum,2. oscillates,3. is zero, or 4. neither?

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path A

path B

point Y (on screen)

starting from top slit

starting from bottom slitpoint Y

At Y the wave1. has a steady maximum,2. oscillates,3. is zero, or 4. neither?

At a LATER TIME after the time shown below

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The green interference fringes shown in the picture on the right are produced on a screen by putting a green laser beam with a wavelength of 550 nm through two identical slits. If the screen is 4 m from the slits, can the spacing between the slits be calculated?

A. Yes

B. No

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The green interference fringes shown in the picture on the right are produced on a screen by putting a green laser beam with a wavelength of 550 nm through two identical slits. If the screen is 4 m from the slits, can you find the spacing between the slits?

A. Yes

B. No

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If the wavelength were reduced, what would happen to pattern on the screen?

A. It would not change.

B. It would squeeze closer together.

C. It would spread further apart.

D. You can’t tell from the information given.

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If the screen were moved closer to the slits, what would happen to pattern on the screen?

A. It would not change.

B. It would squeeze closer together.

C. It would spread further apart.

D. You can’t tell from the information given.

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The figure shows what happens if you put white light through the same slit-screen system. Why are the different colors separated on either side of the center?

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A laser beam passes through a double-slit forming an interference pattern. If we cover one slit with a glass plate, the phase of the wave passing through the glass changes by 180° from what it would have been without the glass. How is the interference pattern changed?

A. The pattern of alternating light and dark spots disappears leaving a single, wide, bright spot.

B. The pattern of alternating light and dark spots disappears leaving the screen dark.

C. The pattern of bright spots spreads out.

D. The pattern of bright spots gets closer together.

E. The pattern reverses itself, bright becoming dark and vice versa.

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If the wavelength is increased, what will happen to the pattern?

A. Get wider

B. Get narrowerC. Stay the same

D. Something else

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If the wavelength is decreased, what will happen to the fringes (narrow peaks shown in red)?

1. Fringes get wider

2. Fringes get narrower

3. Fringes stay the same

4. Something else

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If the wavelength is reduced, what will happen to the squash point (the point where the fringes are driven to zero – shown by the dark arrow)?

A. Move toward the center

B. Move away from the center

C. Stay the same

D. Something else

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When a laser is shone upon a double slit, a closeup of the center of the pattern looks like the figure at the right. If one of the slits is covered (the left one) but the other slit remains open, what will this part of the pattern look like?

• The same.• The left side will be dark.• The right side will be dark.• The whole thing will be bright.• The whole thing will be bright except

for two dark bands at either side.• Something else.

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If the slit is made wider, what will happen to the pattern?A. Get wider

B. Get narrowerC. Stay the same

D. Something else