Definition of magnetic flux VCE 2023 MC Q.6

[Mt Alexander College]

I have question about the suggested answer by Vicphysics.

When I was young, I learned: EMF = – d (PHI) /dt
PHI(uppercase) is the magnetic flux pass through the “coil” and PHI is also equal to N*phi, where phi(lower case) is the flux through individual loop. Therefore, EMF= -N d(phi)/dt

In the VCE question, it seems they have distinguish the words “coil” and “loop”. And the question, it asked “magnetic flux through the coil” not loop. Therefore, I suggest the answer should be B instead of A.

For me, it seems my definition of flux is slightly different from Australia although the physics concepts are the same.

There is a typo in the suggested solution, missed the square.

Man LAM
Laboratory technician
(Mt Alexander College)

[Barbara McKinnon]

Dear Man,
Thanks for your comment. This is a question that comes up quite often in discussion.
I don’t think the upper case PHI notation is helpful or physically correct. There are not N lots of flux. The flux is a measure of the intensity of the field passing through a surface area. The material bounding the surface area is independent of the concept of flux. Maxwell’s equations tell us that a changing magnetic field produces an electric field. This means that if the area through which a magnetic field passes is bounded by a conducting loop and the flux through the loop changes, then an electric field and corresponding EMF is experienced at all points on the loop and, if the loop is continuous a current will flow. More loops, means more points on conductor experiencing an electric field, and hence more current.

Sorry to take so long to notice your post!
Regards,
Barbara

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