A circular coil of resistance ' $R$ ', area ' $A$ ', number of turns ' N ' is rotated about its vertical diameter with angular speed ' $\omega$ ' in a uniform magnetic field of magnitude ' $B$ '. The average power dissipated in a complete cycle is

A coil is wound on a core of rectangular crosssection. If all the linear dimensions of the core are increased by a factor 2 and number of turns per unit length of coil remains same, the self inductance increases by a factor of (Assume, permeability is same)

A graph of magnetic flux $(\phi)$ versus current (I) is shown for 4 different inductors $\mathrm{P}, \mathrm{Q}, \mathrm{R}, \mathrm{S}$. Minimum value of inductance is for inductor

The mutual inductance of two coils is 45 mH . The self-inductance of the coils are $\mathrm{L}_1=75 \mathrm{mH}$ and $\mathrm{L}_2=48 \mathrm{mH}$. The coefficient of coupling between the two coils is