A circular loop of wire of resistance - 0.500 and radius 8.10 cm is in a...

Solution) R = 0.500 ohm

r = 8.10 cm = 8.10×10^(-2) m

I = 3.20 mA = 3.20×10^(-3) A

(a) it indicates increasing magnetic field

(b) dB/dt = ?

I = E/R

E = - d(phi)/dt

phi = B.A = B.(pi)(r^2)

E = (pi)(r^2)(dB/dt)

I = ((pi)(r^2)(dB/dt))/(R)

(dB/dt) = ((I)(R))/((pi)(r^2))

dB/dt = (3.20×10^(-3)×0.500)/((pi)(8.10×10^(-2))^2)

dB/dt = 0.0776 T/s

dB/dt = 77.6 mT/s