Question

A square, conducting loop falls from rest in the xy-plane. There is a uniform magnetic field in the z-direction below the x-axis. The velocity v of the loop is plotted against time t. Which of the following best represents the resulting curve?

Answer 1

Correct Answer is: (d)

At every position, the slope of the v–t graph is equal to the acceleration. This will be equal to g, (a) before the coil enters the magnetic field, and (b) after it has entered the field completely. When part of the coil is in the field, the Ampere force will cause an acceleration less than g. Also, during this phase, as v is still increasing, the Ampere force will increase, and hence the acceleration will decrease gradually.