1. SI unit of inductance is ?

  1. Ohm
  2. Coulomb
  3. Henry
  4. Farad
View Answer

Answer: Option(C)


Memory: SI unit of inductance is farad.

2. Mutual inductance between two magnetically coupled coils depends on ?

  1. Cross-sectional area of the core
  2. Permeability of the core
  3. Number of turns of the coils
  4. All of the above
View Answer

Answer: Option(D)


Memory: Mutual inductance between two coils defined by, M = N1 N2 μr μ0 a / l.

Where,

  • N1 = Number of turns in coil one.
  • N2 = Number of turns in coil two.
  • μr = Relative permeability
  • μ0 = permeability of free space.
  • a = Area of cross-section.
  • l = Length of the conductor.

3. An inductor stores energy in –

  1. Electric field
  2. Magnetic field
  3. Electrostatic field
  4. Free space
View Answer

Answer: Option(B)


Memory: When current flows through an inductor, it stores energy in the magnetic field.

4. An inductor is a

  1. Passive element
  2. Active element
  3. Constant current source
  4. Constant voltage source
View Answer

Answer: Option(A)


Memory: An inductor is a passive element, because, it doesn’t create any energy by itself.

5. An inductor works on the principle of

  1. Faraday’s law
  2. Ohm’s law
  3. Lenz’s law
  4. Coulomb’s law
View Answer

Answer: Option(A)


Memory: An inductor works on the principle of faraday’s laws of electromagnetic induction.

6. An iron core coil its iron core is removed, so as to make it air core.

What will be the inductance in this case ?

  1. Less
  2. More
  3. Remain same
  4. It is no longer an inductor
View Answer

Answer: Option(A)


Memory: No information available.

series connection of inductors

7. In the above figure, inductors are connected in

  1. Series
  2. Parallel
  3. Series-Parallel
  4. Parallel-Series
View Answer

Answer: Option(A)


Memory: Here, inductors are connected in series.

8. An open coil has

  1. Infinite inductance and infinite resistance
  2. Infinite resistance and zero inductance
  3. Zero resistance and zero inductance
  4. Infinite inductance and zero resistance
View Answer

Answer: Option(B)


Memory: When a coil is open, it’s no longer an inductor but resistor.

self inductance formula

9. Self inductance formula is shown above, the variable μr refers to –

  1. Absolute permeability
  2. Relative permeability
  3. Permeability of free space
  4. All of the above
View Answer

Answer: Option(B)


Memory: Option B is correct.

10. Linkage flux per unit current is called ?

  1. Resistance
  2. Conductance
  3. Capacitance
  4. Inductance
View Answer

Answer: Option(D)


Memory: Voltage across an inductor is directly proportional to the rate of change of current with time.

As shown in the below formula.

Inductance Formula
parallel connection of inductors

11. In the above figure, the two inductors L1 and L2 are connected in

  1. Parallel
  2. Series
  3. Parallel-Series
  4. Series-Parallel
View Answer

Answer: Option(A)


Memory: The two inductors are connected in parallel.

12. The Q factor of an inductor would be higher, if it is made of ?

  1. Shorter wire
  2. Longer wire
  3. Thinner wire
  4. Thicker wire
View Answer

Answer: Option(B)


Memory: As Q factor of a coil is inversely proportional to the resistance of the wire.

Longer wire means higher resistance and lower Q-factor.

equivalent inductance between a and b

13. In the above figure, equivalent inductance between A and B is ?

  1. 4H
  2. 3H
  3. 2H
  4. 1H
View Answer

Answer: Option(B)


Memory: Here, in the above figure, the equivalent inductance between points A and B is 3H.

As per the formula, (2*2/2+2)+1+1 = 3.

14. Two coils have self-inductances of 0.9H and 0.1H and a mutual inductance of 0.5H.

The coefficient of coupling between the coils is ?

  1. 5/4
  2. 3/2
  3. 5/3
  4. 4/6
View Answer

Answer: Option(C)


Memory: As per the formula,

coefficient of coupling formula

15. The self inductance of a straight conductor is ?

  1. High
  2. Low
  3. Zero
  4. Infinite
View Answer

Answer: Option(C)


Memory: Until a conductor is twisted it will not exhibit any inductive property, it will just acts as a simple resistor.

As shown in the below image-

Self Inductance