Magnetic hysteresis refers to the lag between magnetization and the external magnetic field. This phenomenon occurs when a material retains some magnetization even after the external field is removed.
Only ferromagnetic materials exhibit magnetic hysteresis because they have domains that remain aligned even after removing the field. This gives rise to the characteristic hysteresis loop.
Magnetic hysteresis is exhibited only by \( {\text{ferromagnetic materials}} \), so the correct answer is (C).
A conducting bar moves on two conducting rails as shown in the figure. A constant magnetic field \( B \) exists into the page. The bar starts to move from the vertex at time \( t = 0 \) with a constant velocity. If the induced EMF is \( E \propto t^n \), then the value of \( n \) is _____.