Question

at time t = 0, a rectangular single-loop coil of resistance R = 5.00 Ohm and dimensions W = 2.00 cm and L = 10.0 cm enters a region of constant magnetic field directed into the page with B = 0.25 T. The length of the region containing the magnetic field is LB = 5.00 cm as shown. The coil is observed to move to the right with the constant speed of v = 2.00 cm/s

#9 W = 2.00 cm L= 10.0 cm L-5.00 cm At time t3.00 s, what is the magnitude of the applied force required to maintain this velocity? (A) 0 (B) 1.00x10 N (C) 1.25×10-5 N D1.75x10 N E) 2.25x1o N

Answer 1

The speed of the coil is 2.00 cm/s. At t=3.00s, the coil will travel a distance of ( 2.00 * 3.00) cm = 6.00 cm and it can be understood that the region with the magnetic field will be completely inside the coil and the change of flux linkage through the coil will be zero and hence there will be no emf induced and no current flowing in the coil and hence no external force required to maintain its velocity.

Option (A) is the correct choice.