11.An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of current must be

12.Higher the self-inductance of a coil,

13.An open coil has

14.Two coils have self-inductances of 10 H and 2 H, the mutual inductance being zero. If the two coils are connected in series, the total inductance will be

15.Which of the following circuit elements will oppose the change in circuit current ?