Question

# E16M.8 Two concentric circular coils lie on a tabletop. The outer coil has a radius r0...

E16M.8 Two concentric circular coils lie on a tabletop. The outer coil has a radius r0 = 25 cm, consists of N = 100 turns of wire, and conducts a sinusoidal 60-Hz alternating current with a maximum value of i0 = 5.0 A. The inner coil is much smaller, with a radius of r = 1.0 cm. It has a single turn (and so is just a loop) with a resistance of R = 0.01 Ω.

A)What approximations do we have to make to calculate the emf and current induced in the small loop? (Hint: Any current flowing in the small loop will create a magnetic field. Why does this complicate things?)

B)Argue that the induced current in the small loop is 90° out of phase with the current in the large coil.

C)If the current in the large coil is going through zero on the way to becoming clockwise, in what direction does the current in the small loop flow?

D)Calculate the maximum emf and the maximum current flowing in the small loop.

E)Argue on the basis of this answer that one of the approximations you made in part (a) is valid.

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