A circular coil has 500 turn of wire and its radius is 5 cm. The self inductance of the coil is

• 25 x 10^-3 mH

• 25 mH

• 50 x 10^-3 H

• 50 x 10^-3 mH

The unit of inductance is

• $\frac{\mathrm{volt}}{\mathrm{ampere}}$

• $\frac{\mathrm{joule}}{\mathrm{ampere}}$

• $\frac{\mathrm{volt}-\mathrm{second}}{\mathrm{ampere}}$

• $\frac{\mathrm{volt}-\mathrm{ampere}}{\mathrm{second}}$

123.

1 Wb/m² is equal to

• 10⁴ G

• 10² G

• 10^-2 G

• 10^-4 G

A steady current of 5 A is maintained for 45 min. During this time it deposits 4.572 g of zinc at the cathode of a voltmeter. ECE of zinc is

• 3.38 × 10^-4 g/C

• 3.397 × 10^-4 g/C

• 3.384 × 10^-3 g/C

• 3.394 × 10^-3 g/C

A magnetising field of 1600 A/m produces a magnetic flux 2.4 x10^-5 Wb in an iron bar of cross-sectional area 0.2 cm². The susceptibility of an iron bar will be

• 1788

• 1192

• 596

• 298

The sun delivers 10⁴ W/m² of electromagnetic flux to the earth's surface. The total power that is incident on a roof of dimension (10 x 10) m²  will be

• 10⁴ W

• 10⁵ W

• 10⁶ W

• 10⁷ W

Current in a circuit falls steadily from 2.0 A to 0.0 A in 10 ms. If an average emf of 200 V is induced, then the self-inductance of the circuit is

• 1 H

• 2 H

• 1/2 H

• 2 H

The polarity of the capacitor in the situation described by Fig.

• Plate A and plate B both positive

• Plate A negative and plate B positive

• Plate A positive and plate B negative

• Plate A and plate B both negative

When a given coil is connected to a 200V, 50 Hz AC source, 1 A current flows in the circuit. The inductive reactance of the coil used is

• $50\sqrt{3} \mathrm{\Omega }$

• $200\sqrt{3} \mathrm{\Omega }$

• $150\sqrt{3} \mathrm{\Omega }$

• $100 \sqrt{3} \mathrm{\Omega }$

The magnetic flux through a circuit of resistance R changes by Δ$\mathrm{\varphi }$ in times Δt. Then, the-total amount of  electric charge that passes in any point in the circuit during this time 'Δt' will be

• $\mathrm{Q} = \frac{∆\mathrm{\varphi }}{\mathrm{R}}$

• $\mathrm{Q} = ∆\mathrm{\varphi } . \mathrm{R}$

• $\mathrm{Q} = \frac{\mathrm{R}∆\mathrm{t}}{∆\mathrm{\varphi }}$

• $\mathrm{Q} = ∆\mathrm{t} . \mathrm{R}$