Diffraction gratiing

[Hopefullpremed]

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What is it for one and two holes, what is the difference? MCAT will ask for this so we can use eqns. for the two sets of experiments?

 

[HawkeyePostOp]

You need a more specific question. Try a review book to brush up.

 

[physics junkie]

I agree. Be more specific. What is what for one hole?

 

[Hopefullpremed]

Why is one hole and two holes counted as different experiments. Equations come out different with a distance d away from the source to the hole and second one has width apart for a. This only works for certain light sources, what does that mean for visible, IR, etc.?

 

[HawkeyePostOp]

what does that mean for visible, IR, etc.?

the equations are all the same, just change lambda

 

[Hopefullpremed]

If light source comes thru a pinhole what's the difference for monochromatic light that is aimed directlly to a selector? Why is theta slightly off for a relflector that if the light comes on a screen vertically if it is located above both?

 

[HawkeyePostOp]

Your question is a little too broad and too conceptual. We need the actual problem to answer it. Also, double slit and single slit diffraction looks like an extremely rare MCAT topic, even constructive interference by itself is rare. I don't think I've ever seen it. It's so rare that if they ask you, they'll probably dump a nice passage on you so that you can get the conceptual stuff squared away. If physics is not your thing, and you can't get some question right, don't ask "why", just fool around with patterns until you get it right.

this site should cover the conceptual stuff

http://hyperphysics.phy-astr.gsu.edu/Hbase/phyopt/diffracon.html#c1

Was there an actual diffraction MCAT practice question with answer choices? If so, post it.

 

[Hopefullpremed]

There was a passage from AAMC Test 1 and they were doing an experiment with a light source through a pinhole. It was displayed on a screen at a right angle 90 degrees above on a screen. 90 degrees below the light reflected. A reflector was at an angle of 15 degrees to the normal. The questions from the passage: What if they used monochromatic light? How does the image change? Larger, smaller, darker, lighter? And why is the reflector at 15 instead of 60?

 

[HawkeyePostOp]

There was a passage from AAMC Test 1 and they were doing an experiment with a light source through a pinhole. It was displayed on a screen at a right angle 90 degrees above on a screen. 90 degrees below the light reflected. A reflector was at an angle of 15 degrees to the normal. The questions from the passage: What if they used monochromatic light? How does the image change? Larger, smaller, darker, lighter? And why is the reflector at 15 instead of 60?

This is not a diffaction grating problem, this is a refraction problem. It sounds like it should get smaller and lighter because light of similar wavelengths would diverge less.

Do you mean AAMC3? I can't find it.

 

[Hopefullpremed]

The passage for that is in AAMC 1, it's an old test and AAMC does not have it on there site anymore. I don't have the solutions/explanations for it either.