Question

A loop is kept so that its center lies at the origin of the coordinate system. A magnetic field has the induction `B` pointing along `Z` axis as shown in the figure

A. No emf and current will be induced in the loop if it rotates about `Z` axis
B. Emf is induced but no current flows if the loop is a fiber when it rotates about `y` axis.
C. Emf is induced and induced current flows in the loop if the loop is made of copper and is rotated about `y` axis.
D. If the loop moves along `Z` axis with constant velocity, no current flows in it.

Answer 1

If the loop rotates about `Z` axis, the variation of flux linkage will be zero. Therefore no emf is induced. Consequently no current flows in the loop
When it rotates about `y`-axis, its flux linkage changes. However, in insulators there can not be motional emf.
If the loop is made of copper, it is conductive therefore induced current is set up.
If the loop moves along the `Z` axis variation of flux linkage is zero. Threfore the emf and current will be equal to zero.