Self inductance and mutual inductance — practice questions

Question 1 · difficulty L1 · recall

Self-inductance is the property by which a changing current in a circuit induces emf

• A. only in a distant unrelated circuit
• B. only in a battery
• C. in the same circuit
• D. only in a resistor with constant current

Question 2 · difficulty L1 · understanding

The SI unit of inductance is

• A. tesla
• B. weber per metre only
• C. farad
• D. henry

Question 3 · difficulty L2 · understanding

The current in an inductor is given by $$\mathrm{I}=(3 \mathrm{t}+8)$$ where $$\mathrm{t}$$ is in second. The magnitude of induced emf produced in the inductor is $$12 \mathrm{~mV}$$. The self-inductance of the inductor _________ $$\mathrm{mH}$$.

Question 4 · difficulty L2 · understanding

Two coils have mutual inductance $$0.002 \mathrm{~H}$$. The current changes in the first coil according to the relation $$\mathrm{i}=\mathrm{i}_0 \sin \omega \mathrm{t}$$, where $$\mathrm{i}_0=5 \mathrm{~A}$$ and $$\omega=50 \pi$$ rad/s. The maximum value of emf in the second coil is $$\frac{\pi}{\alpha} \mathrm{~V}$$. The value of $$\alpha$$ is _______.

Question 5 · difficulty L2 · understanding

Three identical resistors with resistance R = 12$$\Omega$$ and two identical inductors with self inductance L = 5 mH are connected to an ideal battery with emf of 12 V as shown in figure. The current through the battery long after the switch has been closed will be _____________ A.

Question 6 · difficulty L2 · understanding

For the given circuit the current through battery of 6 V just after closing the switch 'S' will be _________ A.

Question 7 · difficulty L2 · understanding

A 10 $$\Omega$$, 20 mH coil carrying constant current is connected to a battery of 20 V through a switch. Now after switch is opened current becomes zero in 100 $$\mu$$s. The average e.m.f. induced in the coil is ____________ V.

Question 8 · difficulty L2 · understanding

The current in a coil of self inductance 2.0 H is increasing according to I = 2 sin(t 2 ) A. The amount of energy spent during the period when current changes from 0 to 2 A is ____________ J.

Question 9 · difficulty L2 · understanding

A 30 cm long solenoid has 10 turns per cm and area of $5 \mathrm{~cm}^2$. The current through the solenoid coil varies from 2 A to 4 A in 3.14 s . The e.m.f. induced in the coil is $\alpha \times 10^{-5} \mathrm{~V}$. The value $\alpha$ is $\_\_\_\_$ .

• A. 60
• B. 12
• C. 120
• D. 34

Question 10 · difficulty L2 · understanding

An inductor of inductance 10 mH having resistance of $100 \Omega$ is connected to battery of E.M.F. 1.0 V through a switch as shown in the figure below. After switch is closed, the ratio of instantaneous voltages across the inductor when the current passing through it is 2 mA and 4 mA is $\_\_\_\_$ .

• A. 4/3
• B. 3/4
• C. 5/3
• D. 3/5