A circular loop of wire is held in a uniform magnetic field, with the plane of the loop perpendicular to the field lines. Which of the following will not cause a current to be induced in the loop?

(a) crushing the loop
(b) rotating the loop about an axis perpendicular to the field lines
(c) keeping the orientation of the loop fixed and moving it along the field lines
(d) pulling the loop out of the field

(c) keeping the orientation of the loop fixed and moving it along the field lines

Explanation:

Ampere's Law current is calculated by evaluating;

∫ B. dl

Here B= magnetic field and dl- length segment in which current is to flow.

Clearly as magnate field lines are perpendicular to the plane of loop having some length ==> dot product will be zero for 90 ° angle and hence current will be zero in the loop i-e we will keep the position of loop and move it along field lines !

double the distance = divide strength by 4

seeing the graph would