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# Really Difficult Lenz' Law Watch

1. http://qualifications.pearson.com/co...e_20110621.pdf

for question 6 of the paper above the answer is b but why?
2. (Original post by runny4)
http://qualifications.pearson.com/co...e_20110621.pdf

for question 6 of the paper above the answer is b but why?
It isn't actually necessary to understand the physics to answer it correctly (the hall mark of a bad question)... two of the answers would only affect the magnitude of the current in coil X and the other one would do nothing leaving only one answer remaining (B) to be correct.

It isn't actually necessary to understand the physics to answer it correctly (the hall mark of a bad question)... two of the answers would only affect the magnitude of the current in coil X and the other one would do nothing leaving only one answer remaining (B) to be correct.Isn't there something to do with change in flux? decreasing the resistance or moving the coils closer would result in increasing magnetic flux through X while switching off the current in Y would result in decreasing flux through X leading to the induced current being in the other direction. No change would obviously do nothing.
3. (Original post by natninja)
It isn't actually necessary to understand the physics to answer it correctly (the hall mark of a bad question)... two of the answers would only affect the magnitude of the current in coil X and the other one would do nothing leaving only one answer remaining (B) to be correct.

It isn't actually necessary to understand the physics to answer it correctly (the hall mark of a bad question)... two of the answers would only affect the magnitude of the current in coil X and the other one would do nothing leaving only one answer remaining (B) to be correct.Isn't there something to do with change in flux? decreasing the resistance or moving the coils closer would result in increasing magnetic flux through X while switching off the current in Y would result in decreasing flux through X leading to the induced current being in the other direction. No change would obviously do nothing.
oh ok thank you

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