aamc c/p section bank #10

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aamc c/p section bank #10

Postby mshah » Wed Dec 13, 2017 9:39 pm

Confused on how the answer is B versus D? How are you supposed to know from the passage that the higher energy goes to higher frequency if they are discussing amplitudes in the passage? Why is it not D, less photons less energy?
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Re: aamc c/p section bank #10

Postby NS_Tutor_Andrew » Thu Dec 14, 2017 2:16 pm

Hi mshah,

This question involves a combination of passage information & outside knowledge.

What we need to take away from the passage is that laser type A is used for a higher-energy bond than laser type C, so we we need to look for an answer choice that describes laser A as being higher-energy than laser C.

The outside knowledge that we need to have is: (1) E = hf, meaning that energy is directly proportional to frequency; and (2) c = λf, which means that wavelength and frequency are inversely proportional -- and we can combine this with E = hf to derive E = hc/λ, meaning that energy and wavelength are inversely related. So, ↑ energy = ↑ frequency and ↓ wavelength, while ↓ energy = ↓ frequency and ↑ wavelength.

Therefore, we need to look for an answer choice that describes laser A having a greater frequency or a lower wavelength than laser C.

A is irrelevant. B fits the bill. C is the opposite of what we're looking for.

D is another way of looking at energy, but it would imply that laser A would have less energy than laser C, so it's also the opposite of what we're looking for too.

The key takeaway point in terms of content is that E = hf is absolutely essential MCAT knowledge. It, along with the related equation, E = hc/λ, would easily make my list of the top 5 physics equations/concepts you should be familiar with for the MCAT.

Hope this is helpful & best of luck as you prepare!
Andrew D.
Content Manager, Next Step Test Prep.

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