A coil of resistance 20$\Omega$ and inductance 5H has been connected to a 200 V battery. The maximum energy stored in the coil is

(1) 250 J

(2) 125 J

(3) 500 J

(4) 100 J

The inductance of a coil is 60μH. A current in this coil increases from 1.0 A to 1.5 A in 0.1 second. The magnitude of the induced e.m.f. is 

(1) 60 × 10^–6 V

(2) 300 × 10^–4 V

(3) 30 × 10^–4 V

(4) 3 × 10^–4 V

The self inductance of a coil is L. Keeping the length and area same, the number of turns in the coil is increased to four times. The self inductance of the coil will now be 

(1) $\frac{1}{4}L$

(2) L

(3) 4 L

(4) 16 L

Pure inductance of 3.0 H is connected as shown below. The equivalent inductance of the circuit is

(1) 1 H

(2) 2 H

(3) 3 H

(4) 9 H

If a current of 10 A flows in one second through a coil, and the induced e.m.f. is 10 V, then the self-inductance of the coil is 

(1) $\frac{2}{5}H$

(2) $\frac{4}{5}H$

(3) $\frac{5}{4}H$

(4) 1 H