A thin non-conducting ring of mass

PHYSICS · Single correct · AP · Physics C: Electricity and Magnetism · Electromagnetic Induction · Electromagnetic Induction

Problem

m

, radius

a

, and charge

q

can rotate freely about its vertical axis. Initially, the ring is at rest in a horizontal position and no magnetic field is present. At

t=0

, a uniform vertically downward magnetic field is switched on and increases according to

B=B_0t

. Neglect magnetism induced by the rotational motion of the ring. Find the instantaneous power developed by the electric force acting on the ring at

t=1\,\mathrm{s}

. (a)

\frac{2q^2B_0^2a^2}{14m}

(b)

\frac{q^2B_0^2a^2}{8m}

(c)

\frac{3q^2B_0^2a^2}{m}

(d)

\frac{q^2B_0^2a^2}{4m}