B Recent question on NYS regents exam, is it accurate?

[superdave]

A beam of which of the following will produce a magnetic field?

Gamma rays
X-Rays
Neutrons
Protons

Now, the answer they want is protons, to emphasize that moving charged particles create magnetic fields. But is that really accurate? Do moving photons NOT consist of a changing magnetic field that propagates as it travels, and could be described as creating the field?

OR, couldn't you think about it as the field always exists everywhere, but the moving protons, or the moving photons are only creating changes in the EM field?

 

[Vanadium 50]

The instructions say to pick the best answer. Which answer is the best?

 

[Dale]

Do moving photons NOT consist of a changing magnetic field that propagates as it travels, and could be described as creating the field?

That is true, but similarly the neutron has a magnetic dipole moment.

 

[superdave]

That is true, but similarly the neutron has a magnetic dipole moment.

So I guess my point is that it's a bad question.

 

[Vanadium 50]

Why? There is a best answer.

 

[ogg]

I agree that the question is "bad" in the sense that all 4 answers correctly cause a magnetic field. OTOH, the purpose of a test is often to distinguish between groups. For instance, if all geniuses believed they were the center of the world, then the T/F question: "T/F: I am the center of the world." would help separate them from people with 'lesser' intelligence, REGARDLESS of whether or not the answer was true, and actually regardless of whether the question even makes sense. A DIFFERENT point is that the question you posted actually is testing your ability to guess what the people who put that question into the test INTENDED to be the right answer in the test taking context. Now, that's a much more complex task, so serves to test both content and mental agility of the student. If you want, you could write to the Regents and point out that the answers are all technically correct and challenge its use. Probably, to be heard, you'd have to find out more about the way the test was designed and who approved this question for inclusion and then write them along with some authoritative confirmation of your claim - preferably from a Physics professor (Nobel Prize winner > Harvard > SUNY > podunk community college).

 

[DocZaius]

I agree that a question where all answers are technically correct is a bad one. If the test maker has to say "Oh but you knew what I meant!", then the question was written in a lazy way. The question should have had caveats that would make a single answer not just the one intended to be the correct, but also the only one technically correct. And yes, I'm aware that can result in too much of a hint being given, but that's the price you pay to not punish someone for answering in a way that is not actually wrong. The irony of this practice of lazy-question-writing is that it makes those more familiar with the subject more likely to answer "wrongly", while those ignorant of any of the subtleties just think "only moving charged particles produce changes in magnetic fields" and answer "correctly" immediately.

Also, the word "best" in "pick the best answer" is ambiguous. Maybe I consider the best answer in this context to be the one in which the produced magnetic fields are most concentrated in the beam. Maybe I think that because the question mentioned only the beam and not the surrounding space, that the answer should be the one in which the resulting magnetic field is in the beam and nowhere else. "Oh but you knew what I meant!"? I shouldn't have to read into your intents as a test writer. My job as a test taker isn't to wonder what's in the head of the test maker. It's to answer correctly according to the words on the paper.

 

[houlahound]

It is appears to becoming quiet routine to set multiple choice response with all correct answers.

Never seen the literature on it, just know it is a common technique.

 

[Vanadium 50]

This is a physics exam, not a law exam. Does anyone honestly think that A, B and C are better answers than D? That is, that you would honestly expect a good student to answer A, B or C?

 

[lychette]

That is true, but similarly the neutron has a magnetic dipole moment.

does this mean that a beam of neutrons produces a magnetic field ?...I don't think so

 

[lychette]

which of the four beams can be deflected with a magnetic field?

 

[Dr Transport]

Having grown up in Upstate NY, and I took the Regents exam in Physics a bunch of years ago, I suspect the answer they were looking for was proton. simply because it is the only charged particle in the list. I also posed the question to my sister who is a physics teacher who gave this exam and the answer is proton, plain and simple.

 

[sophiecentaur]

Multiple choice questions are a very limited way to test 'understanding'. If you give the answer that the system expects then you get the mark. If you sit and think about the deeper meaning of the question then you are wasting time (possibly missing our on marks later on) and there is no record of the intellectual contribution your brain has been making at the time.
The only multiple choice questions that are valid are numerical ones. I hate most of them. The only good multiple choice papers I ever saw were in the Nuffield A level Physics and involved choosing combinations of answers to clever worded questions. The distractors were as important as the correct answers and they were HARD. Sorted the men from the boys (and the female equivalent).

 

[houlahound]

I used to think that but thru recent discussion with pro exam writers, not subject related , more work goes into constructing MC than most other question types.

We rarely experience that in the hard sciences tho.

 

[sophiecentaur]

There you go.