#19 - Specific Reference

[hfsports429]

Hi,

This question asks what inference we can make about the blackbody objects described in the second paragraph. I had a lot of trouble with this question since none of the answers seemed to fit. B,C,D,E were all no for me on the first go around because I thought all of them were way too strong and could not be proven in the text. I thought A was the softest of these answers, so I picked it at first. But then I went back and changed my answer after I saw in lines 19-22:

"Physicists can monitor the radiation coming from a blackbody object and be confident that they are observing its thermal radiation and not simply reflected radiation that originated elsewhere."

Doesn't this seem like the opposite of answer A ("Radiation reflected by and radiation emitted by an object are difficult to distinguish from one another.") If not, where in the text is this answer supported?

Thanks.

[David Boyle]

Hi,

This question asks what inference we can make about the blackbody objects described in the second paragraph. I had a lot of trouble with this question since none of the answers seemed to fit. B,C,D,E were all no for me on the first go around because I thought all of them were way too strong and could not be proven in the text. I thought A was the softest of these answers, so I picked it at first. But then I went back and changed my answer after I saw in lines 19-22:

"Physicists can monitor the radiation coming from a blackbody object and be confident that they are observing its thermal radiation and not simply reflected radiation that originated elsewhere."

Doesn't this seem like the opposite of answer A ("Radiation reflected by and radiation emitted by an object are difficult to distinguish from one another.") If not, where in the text is this answer supported?

Thanks.

Hello hfsports429,

Actually, the line that you quote above helps prove answer A. The reason that blackbody objects are preferred is that it is hard to tell emitted radiation from reflected radiation. But with blackbody objects, scientists know there is little reflected radiation to cause problems.

Hope this helps,
David

[Pragmatism]

I chose the wrong answer for this section, only because everything else seemed wrong. My reasoning for choosing answer choice B, which was a hard pill to swallow, was the phrase, "with little or no reflective capability." Nevertheless, the word "any" should have given it away, but it seemed the least far fetched answer choice of them all.

Anyways, now to the right answer, I am confused about the phrasing to this answer choice. I understand, what the answer choice is saying, but I am more flummoxed by the question itself. Is the question being interpreted as "why does the the experiment require black velvet or soot?" If so, then this answer choice A makes sense, but if not, then I find lines 19-22 saying the contrary to the answer choice. My confusion with answer choice A lies in the phrase "object are difficult to distinguish from one another." So, since the question stem ask's us to "infer from the description of blackbody objects" this makes no sense, if "description" is to be viewed as what is explicitly stated in the passage. However, if by "description" they mean the word "explanation," then answer choice A makes more sense. Could you please help me with this.

Thank you

[Francis O'Rourke]

Hi Pragmatism,

It sounds like you are reading a lot into this question that is not present. The question is not specifically asking us about the necessity of using blackbody objects. Rather, the question stem is merely asking us to do two things:

1. Focus on the part of the passage (paragraph 2) where the author wrote about blackbody objects.
2. Select one of the following statements that must be true based on that part of the passage.

Answer choice (A) tells us that it is difficult to distinguish between reflected and emitted radiation when both are present. Lines 19-22 do not contradict this statement. Since we know that blackbody objects have zero, or near zero, reflected radiation, there is no question about whether the radiation that scientists are seeing from these objects is reflected or emitted, because there is no reflected radiation present. It is still true that when both types of radiation are present, it is difficult to distinguish them.

Let me know if this helps, or if you still have questions about this one!

[Pragmatism]

The moment when the caveman escaped from the shackles that were confining him, and he saw the light for the first time in Plato's Cave Allegory, is what just happened here to me. Eureka!