0
$\begingroup$

Q: a solenoid with ends marked a and b is suspended so that the core can rotate in the horizontal plane. A current is maintained in the coil so that the electrons move clockwise when viewed from end A towards end B. How will the coil align itself in earth's magnetic field?

Now An answer I have (from an answer bank our teacher gave us) is "end A will point towards the geographic south pole."

Meaning that end A becomes the south pole of the magnet. Now I don't understand how.

Since the question says that the electrons move clockwise when viewed from end A, so that means the conventional current moves counter-clockwise when viewed from end A. If we apply the right hand rule for solenoids ( or atleast the version my book has: the way our fingers curl is the current's direction and our thumb is the field's), when you look from end A towards end B the field is directed towards you, making end A the north pole of the solenoid. Right...?

Any help is appreciated.

$\endgroup$
1
$\begingroup$

Your reasoning is sound and (if I may say so) very nicely presented. End A is indeed the North pole of the solenoid. 'North", in this context, is short for "North-seeking", which means geographically North-seeking. So unless we've both done something silly, the answer you've been given is wrong.

$\endgroup$
  • $\begingroup$ Thanks for the compliment. I thought I had made a mistake at first as well but looks like the mistake is on the book's end $\endgroup$ – Dahen Oct 13 '17 at 11:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.