1. SI unit of inductance is ?
Memory: SI unit of inductance is farad.
2. Mutual inductance between two magnetically coupled coils depends on ?
- Cross-sectional area of the core
- Permeability of the core
- Number of turns of the coils
- All of the above
Memory: Mutual inductance between two coils defined by, M = N1 N2 μr μ0 a / l.
- 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 –
- Electric field
- Magnetic field
- Electrostatic field
- Free space
Memory: When current flows through an inductor, it stores energy in the magnetic field.
4. An inductor is a –
- Passive element
- Active element
- Constant current source
- Constant voltage source
Memory: An inductor is a passive element, because, it doesn’t create any energy by itself.
5. An inductor works on the principle of –
- Faraday’s law
- Ohm’s law
- Lenz’s law
- Coulomb’s law
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 ?
- Remain same
- It is no longer an inductor
Memory: No information available.
7. In the above figure, inductors are connected in –
Memory: Here, inductors are connected in series.
8. An open coil has –
- Infinite inductance and infinite resistance
- Infinite resistance and zero inductance
- Zero resistance and zero inductance
- Infinite inductance and zero resistance
Memory: When a coil is open, it’s no longer an inductor but resistor.
9. Self inductance formula is shown above, the variable μr refers to –
- Absolute permeability
- Relative permeability
- Permeability of free space
- All of the above
Memory: Option B is correct.
10. Linkage flux per unit current is called ?
Memory: Voltage across an inductor is directly proportional to the rate of change of current with time.
As shown in the below formula.
11. In the above figure, the two inductors L1 and L2 are connected in –
Memory: The two inductors are connected in parallel.
12. The Q factor of an inductor would be higher, if it is made of ?
- Shorter wire
- Longer wire
- Thinner wire
- Thicker wire
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.
13. In the above figure, equivalent inductance between A and B is ?
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 ?
Memory: As per the formula,
15. The self inductance of a straight conductor is ?
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-