You are given a length L of wire and told to form it into a current loop

Question:

You are given a length L of wire and told to form it into a current loop so as to produce the maximum possible emf when the loop is placed in a time-varying magnetic fi eld. You investigate the three loop geometries in Figure Q21.10: a long, thin rectangle; a square; and a circle. Which one will give the largest emf?

1 mm Figure Q21.10