If all linear dimensions of an inductor are tripled, then self-inductance will become (keeping the total number of turns per unit length constant)

1.  3 times

2.  9 times

3.  27 times

4. 1/3 times

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

A coil and a bulb are connected in series with a DC source, and a soft iron core is then inserted in the coil. Then 

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

The adjoining figure shows two bulbs \(B_1\) and \(B_2\) resistor \(R\) and an inductor \(L\). When the switch \(S\) is turned off 

In the figure magnetic energy stored in the coil is 

1. Zero

2. Infinite

3. 25 joules

4. None of the above

If induction of magnetic field at a point is B and energy density is U, then which of the following graphs is correct?

1. 

2. 

3. 
4.