1. The core of a coil has a length of 200 mm. The inductance of coil is 6 mH. If the core length is doubled, all other quantities, remaining the same, the inductance will be ?

3 mH

12 mH

24 Mh

48 mH

Answer: 3 mH

Explanation:


2. The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as ?

self-inductance

mutual inductance

series aiding inductance

capacitance

Answer: self-inductance

Explanation:


3. ln an iron cored coil the iron core is removed so that the coil becomes an air cored coil The inductance of the coil will ?

increase

decrease

remain the same

initially increase and then decrease

Answer: decrease

Explanation:


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

64 A/s

32 A/s

16 A/s

4 A/s

Answer: 4 A/s

Explanation:


5. Which of the following circuit element stores energy in the electromagnetic field ?

Inductance

Condenser

Variable resistor

Resistance

Answer: Inductance

Explanation:


6. A coil with negligible resistance has 50 V across it with 10 mA. The inductive reactance is ?

50 ohms

500 ohms

1000 ohms

6000 ohms

Answer: 6000 ohms

Explanation:


7. A conductor carries 125 amperes of current under 60ยบ to a magnetic field of 1.1 tesla. The force on the conductor will be nearly ?

50 N

120 N

240 N

480 N

Answer: 120 N

Explanation:


8. For a purely inductive circuit which of the following is true ?

Apparent power is zero

Relative power is zero

Actual power of the circuit is zero

Any capacitance even if present in the circuit will not be charged

Answer: Actual power of the circuit is zero

Explanation: