A square, single-turn wire loop 1.00 cm on a side is placed inside a

A square, single-turn wire loop 1.00 cm on a side is placed inside a solenoid that has a circular
cross section of radius 3.00 cm, as shown in the figure below. The solenoid is 25.0 cm long and
wound with 110 turns of wire. If the current in the solenoid is 4.00 A, find the flux through the
loop. T middot m2 If the current in the solenoid is reduced to zero in 2.00 s, find the magnitude
of the average induced emf in the loop. V


Solution


First, find the mag field of the solenoid. This is given by
B = u N i / L = 4pix10^-7 * 110 * 4..25 = 0.0022117 Tesla
Then the flux is just the B field times the area of the square loop
flux = B * area = 0.0022117 * 0.01^2 = 2.2117 x 10^-7 T-m^2
Then for the avg emf induced...
emf = change in flux / time = (2.217 x 10^-7 - 0 ) / 2.00 =
= 1.108 x 10^-7 Volts