# 12 Physics Questions - Light and Color

Discussion in 'BlackHat Lounge' started by maxxwilliams, Apr 19, 2012.

1. ### maxxwilliamsJunior Member

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Hi guys. I have a few questions I would like to get your opinions on. I am not sure about a couple of them, so I want to se what some physics experts think the answers are:

[h=3]Question 1[/h]
1. Light from two coherent, in-phase point sources interferes at some point P. Is the interference at P constructive or destructive if the distance from the first point to P differs
from that from the second point to P by 3 wavelengths?

 A. constructive B. destructive C. in between D. depends on wavelength

[h=3]Question 2[/h]
1. Is a lens coating that is designed to transmit the blue region of the visible spectrum thicker or thinner than one designed for the central (green) region?

 A. thicker B. thinner C. the same D. depends on the index of refraction of the lens

[h=3]Question 3[/h]
1. The colors of a soap bubble or an an oil film on water are produced by:

 A. selective absorption and reflection B. diffraction C. interference D. refraction

[h=3]Question 4[/h]
1. A thin film of oil (n=1.4) is floating on a piece of crown glass (n=1.55). We shine light onto the film. The reflection of the light off the bottom surface of the film is

 A. hard, with no shift (zero phase change) B. soft, with a shift of half a wavelength (phase change of 180 degrees) C. hard, with a shift of half a wavelength (phase change of 180 degrees) D. there is no reflection - all is transmitted

[h=3]Question 5[/h]
1. Referring to the setup in Question 4, the reflection of light off the top surface of the oil film is

 A. hard, with a shift of half a wavelength (phase change of 180 degrees) B. soft, with a shift of a quarter of a wavelength (phase change of 90 degrees) C. hard, with no shift (zero phase change) D. there is no reflection - all light is transmitted

[h=3]Question 6[/h]
1. Referring again to the setup in Question 4, suppose we shine light of wavelength 550 nm onto the film. The thickness of the film is 200 nm (nanometers). Remember that index of refraction of the oil is 1.4, while that of crown glass is 1.55. What is the wavelength of that light when it's inside the film?

 A. 550 nm B. 275 nm C. 183 nm D. 367 nm

[h=3]Question 7[/h]
1. Referring to the setup in Question 4 again, what is the total wavelength shift between the beam reflected off the top of the oil film and the beam reflected off the bottom of the oil film?

 A. no wavelength shift (zero degree phase change) B. half a wavelength shift (180 degree phase change) C. a quarter of a wavelength shift (90 degree phase change) D. it's about equal to the thickness of the film

[h=3]Question 8[/h]
1. When you look at a single slit diffraction pattern produced on a screen by light of a single wavelength, you see a bright central fringe and a number of other fringes on either side, their intensity decreasing with distance from the central fringe. If the wavelength of the light is increased:

 A. The fringes in the pattern move farther apart B. The fringes in the pattern move closer together C. The central fringe gets fainter D. The outer fringes get fainter and also move farther apart

[h=3]Question 9[/h]
1. The figure below shows two unknown devices, each of which separates (disperses) white light into its spectrum. The positions of the two wavelengths are shown on each screen. Two optical devices that can produce cases A and B (respectively) are

 A. a concave mirror and a convex lens B. a ray box and a prism C. a transmission grating and a prism D. a transmission grating and a ray box

[h=3]Question 10[/h]
1. Diffraction occurs when light passes through a

 A. Pinhole B. Narrow slit C. Lens D. All of the above

[h=3]Question 11[/h]
1. Light impinges on a slit but suffers very little diffraction. We conclude that the wavelength of the light is

 A. Much shorter than the slit width B. Much longer than the slit width C. About the same order as the slit width D. We cannot say anything about the wavelength

[h=3]Question 12[/h] When you hold up a CD to the light, you see a colorful rainbow on its surface. This occurs because the CD acts as a _____ which produces color by _______

 A. Prism; Diffraction B. Transmission Grating; Interference C. Reflection Grating; Interference D. Prism; Dispersion

2. ### marusiaSenior Member

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1. A

3. C

10. B

12. C

Some of those need the diagram to figure out the answer. Optical physics isn't my strong suit, but I did what I could. :-/

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4. ### Nigel FarageBANNEDBANNED

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Lol, this again. You want "opinions' on the answers, roflmao. What happened, did you get artificially promoted in school to the point that you can't do the homework?
C'mon, tell us the truth. You haven't the requisite background to understand your current classes, because you've been passed on despite the fact you don't measure up.

Have you cheated all the way to this point? Or have you been receiving undeserved passes for other reasons. Basketball? ROFLMAO
Or reasons other than that, hmm??
Maybe you should start a "Journey" thread, LMAO!

Hell, that's a great idea! Start a cheating blog, create a community of fellow-cheaters, have cheating seminars and cheating e-books.

Here's your Motto (in English) "Too Dumb to Pass, but Smart Enough to Cheat". I'll look up the latin translation on Google, or maybe set up a fiverr gig and have someone else give me the answer, LOL.

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6. ### axcerRegular Member

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Not again!!!!!!!

7. ### maxxwilliamsJunior Member

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These comments make me laugh; and I can understand I may seem annoying. But some of you people just need more pleasure in life. Perhaps intercourse, vacations, nights out, something to ease off the tension.

In response to some people that, to me at least, seem like "haters," I already have my answers ready to turn in. I do this so I get more viewpoints on what people think the correct answers are. This way I can double check my answers with the rest. It is funny that people think I am a cheat just for putting up a thread related to school-questions, when they have no idea what my strategy is.

Some of you just need to get a girlfriend/boyfriend. It is fun messing with a partner if you are irritated by something. Perhaps you had a bad day, and need someone to take the anger out upon. I ask some of you to do just that. It is pretty fun, and that's how a relationship builds up.

My point is so that you don't waste your own time commenting on threads that you have no idea about, rather just annoy teasing your partner. That way, you can have a more open and social life, and not cramp up on what everyone is posting online, being right there to comment in total awe of what the thread is asking; just cool down, ignore the thread and move on. If you don't like me, or perceive me as a cheater trying to get the easy way out, then fine, go ahead and think that. But is it really necessary to waste your own time, as well as mine, as I have to read the garbage you just wrote? And smile

C'mon now folks! Lol.

And Nigel Farage, I am a soccer player. A little bit too short for basketball, but you were close. I will pm you once (hopefully) I make it as a pro. I'll even invite you to a match. But since you mentioned me as a cheater, maybe I get my little "win-any-way-possible" habit from sports. I am very competitive and always want to win. So, maybe now you know that I am merely trying to get EVERY question correct, rather than cheat.

8. ### 75INZRegular Member

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I love these responses that people give, long winded and attempting to throw out subtle insults while trying to make themselves feel better.

Whatever makes you sleep at night, though.

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