Part of a single rectangular loop of wire with dimensions .35 m by .75 m (.35 is the height and .75 is the length) is situated inside a region of uniform magnetic field of 0.395 T. The total resistance of the loop is 0.690 Ω.

Question

Part of a single rectangular loop of wire with dimensions .35 m by .75 m (.35 is the height and .75 is the length) is situated inside a region of uniform magnetic field of 0.395 T. The total resistance of the loop is 0.690 Ω.
Calculate the force required to pull the loop from the field (to the right) at a constant velocity of 6.36 m/s. Neglect gravity.

Elena · Accepted Answer

The induced emf in the loop is ε =dΦ/dt =d(BwL)/dt=Bwv, The current is I = ε/R = Bwv/R The force is F =(Bw)^2v/R (W =0.35 m, B = 0.395 T, v =6.36 m/s, R= 0.690 Ω)