## Optics B/C

UTF-8 U+6211 U+662F
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### Re: Optics B/C

jonboyage wrote:
UTF-8 U+6211 U+662F wrote:All right, my question killed the marathon, so I'll just post the answer.

1) Fill in the blank: Stars moving toward us appear more _ (color).
2) Why is this?

Blue; wavelength decreases due to Doppler shift

Good! Although I wanted you to explain what the Doppler effect is. Your turn anyway.

jonboyage
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### Re: Optics B/C

1. What is the power, in diopters, of a lens with n=1.6, r1=3cm, r2=-10cm, D=1cm?

2. Is the lens: Bi-convex, bi-concave, plano-convex, plano-concave, convexo-concave, or concavo-convex?

3&4. Repeat questions 1 and 2 for a lens with n=1.4, r1=5cm, r2=infinity, D=.25cm.

5. Which of these lenses is more likely to experience more profound spherical of aberration? How do you know?
I was in a bin

Rustin '19
UPenn '23

UTF-8 U+6211 U+662F
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### Re: Optics B/C

jonboyage wrote:1. What is the power, in diopters, of a lens with n=1.6, r1=3cm, r2=-10cm, D=1cm?

2. Is the lens: Bi-convex, bi-concave, plano-convex, plano-concave, convexo-concave, or concavo-convex?

3&4. Repeat questions 1 and 2 for a lens with n=1.4, r1=5cm, r2=infinity, D=.25cm.

5. Which of these lenses is more likely to experience more profound spherical of aberration? How do you know?

Oh boy...

jonboyage
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### Re: Optics B/C

UTF-8 U+6211 U+662F wrote:
jonboyage wrote:1. What is the power, in diopters, of a lens with n=1.6, r1=3cm, r2=-10cm, D=1cm?

2. Is the lens: Bi-convex, bi-concave, plano-convex, plano-concave, convexo-concave, or concavo-convex?

3&4. Repeat questions 1 and 2 for a lens with n=1.4, r1=5cm, r2=infinity, D=.25cm.

5. Which of these lenses is more likely to experience more profound spherical of aberration? How do you know?

Oh boy...

Almost...

I was in a bin

Rustin '19
UPenn '23

UTF-8 U+6211 U+662F
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### Re: Optics B/C

jonboyage wrote:
UTF-8 U+6211 U+662F wrote:
jonboyage wrote:1. What is the power, in diopters, of a lens with n=1.6, r1=3cm, r2=-10cm, D=1cm?

2. Is the lens: Bi-convex, bi-concave, plano-convex, plano-concave, convexo-concave, or concavo-convex?

3&4. Repeat questions 1 and 2 for a lens with n=1.4, r1=5cm, r2=infinity, D=.25cm.

5. Which of these lenses is more likely to experience more profound spherical of aberration? How do you know?

Oh boy...

Almost...

Actually, if we're using Cartesian sign convention

Why do dry roads sometimes seem like they are wet to a passing motorist?

jonboyage
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### Re: Optics B/C

UTF-8 U+6211 U+662F wrote:
jonboyage wrote:
UTF-8 U+6211 U+662F wrote:
Oh boy...

Almost...

Actually, if we're using Cartesian sign convention

Why do dry roads sometimes seem like they are wet to a passing motorist?

Next problem's answer: I think this is what you're referring to but I may be completely off
I was in a bin

Rustin '19
UPenn '23

UTF-8 U+6211 U+662F
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### Re: Optics B/C

jonboyage wrote:
UTF-8 U+6211 U+662F wrote:Why do dry roads sometimes seem like they are wet to a passing motorist?

Next problem's answer: I think this is what you're referring to but I may be completely off

jonboyage
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### Re: Optics B/C

How do helium-neon lasers work? (Incorporate the explanation of population inversion in your answer)
I was in a bin

Rustin '19
UPenn '23

c0c05w311y
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### Re: Optics B/C

jonboyage
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### Re: Optics B/C

c0c05w311y wrote:

That was a really nice, detailed explanation. Now just remember that for the competition
I was in a bin

Rustin '19
UPenn '23

c0c05w311y
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### Re: Optics B/C

Consider an f/4 refracting telescope with an aperture diameter of 550mm, and an f/14 telescope.

a. which telescope would be better for taking pictures?
b. which telescope would be better for making precise observations, and why?
c. Name three typical abberations. What is a coma and how do you fix it?
d. If the eyepiece of the f/4 telescope has a focal length of 12mm, what is the magnification of the telescope? What is the angular resolution for IR light?

if i messed something up let me know

UTF-8 U+6211 U+662F
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### Re: Optics B/C

c0c05w311y wrote:Consider an f/4 refracting telescope with an aperture diameter of 550mm, and an f/14 telescope.

a. which telescope would be better for taking pictures?
b. which telescope would be better for making precise observations, and why?
c. Name three typical abberations. What is a coma and how do you fix it?
d. If the eyepiece of the f/4 telescope has a focal length of 12mm, what is the magnification of the telescope? What is the angular resolution for IR light?

if i messed something up let me know

c0c05w311y
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Location: Carnegie Mellon University

### Re: Optics B/C

UTF-8 U+6211 U+662F wrote:
c0c05w311y wrote:Consider an f/4 refracting telescope with an aperture diameter of 550mm, and an f/14 telescope.

a. which telescope would be better for taking pictures?
b. which telescope would be better for making precise observations, and why?
c. Name three typical abberations. What is a coma and how do you fix it?
d. If the eyepiece of the f/4 telescope has a focal length of 12mm, what is the magnification of the telescope? What is the angular resolution for IR light?

if i messed something up let me know

Looks pretty good! sorry ive taken so long to get back to you, I've been sick plus I had my regional competition on wednesday. The reason, according to wikipedia, that higher f numbers are better for precise measurements and such is that it is easier to reduce aberrations. Also, I wasn't really thinking about the magnification for part a but yes, if you assume the diameter is the same, there is more magnification. I was thinking about the fact that if you assume the focal length is the same, the diameter is bigger for a smaller f number, which means you get more light for pictures in a smaller amount of time.

UTF-8 U+6211 U+662F
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### Re: Optics B/C

What is the primary difference between gamma and X rays? (Don't say wavelength/frequency/energy since there isn't a defined boundary between gamma and X rays there)

Tom_MS
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### Re: Optics B/C

UTF-8 U+6211 U+662F wrote:What is the primary difference between gamma and X rays? (Don't say wavelength/frequency/energy since there isn't a defined boundary between gamma and X rays there)

Gamma rays are produced by nuclear processes (like nuclear decay) and particle interactions (like annihilation of particle-antiparticle pairs). X-rays are produced by electrons outside of the nucleus.