[2018EM/QUIZ-06]

Electrodynamics Oct 31, 2018
Quiz-VI

Feynman gives, the arrangement shown in figure below, as a counter example of
flux rule. When the disc of radius \(a\) rotates, there is no change in flux
linked with the disc, yet there will be an induced e.m.f. and a current.

Now assume that instead of a bar magnet, we have a uniform
magnetic field of strength \(B_0\) perpendicular to the disc.

Assume that the resistance of the copper disc can be
neglected. You may assume that the magnetic field is
perpendicular to the disc. Answer the following questions.

1. The flux linked with the disc does not change, but there will be an induced current. Explain WHY?
2. Use Maxwell's equations compute the induced e.m.f. in the circuit when the copper disc rotates with angular velocity \(\omega\).
3. What path would you use to find e.m.f.? Justify your choice.
4. Compute Joule heat generated in the circuit per sec.