In the figure below, a uniform magnetic field decreases at a constant rate dB /
ID: 1520446 • Letter: I
Question
In the figure below, a uniform magnetic field decreases at a constant rate dB/dt = K, where K is a positive constant. A circular loop of wire of radius a containing a resistanceR and a capacitance C is placed with its plane normal to the field.
(a) Find the charge Q on the capacitor when it is fully charged. (Use the following as necessary: C, a, and K.)
Q =
(b) Which plate, upper or lower, is at the higher potential?
upper plate
lower plate
(c) Discuss the force that causes the separation of charges.
Explanation / Answer
induced emf = rate of change in magnetic flux = d(NBA)/dt
= N A db/dt
= (pi a^2)(-K)
when fully charged then voltage across capacitor will be pi a^2 K.
Q = C V
Q = pi a^2 C K
b) upper plate
c) due to change in magnetic field. eletric force is acted .
so current flows to oppose change in magnetic flux.