# MCQ on Inductance Important Questions

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## MCQ on Inductance

Q1. What is an inductor?

A) A device that stores electrical charge

B) Its converts electrical energy into mechanical energy

C) A device that stores magnetic energy

D) A device that generates electrical energy

Answer: C) A device that stores magnetic energy

Q2. What is the unit of inductance?

B) Hertz

C) Henry

D) Ohm

Q3. What is the symbol used to represent an inductor in an electrical circuit diagram?

A) R

B) C

C) L

D) I

Q4. What happens to the inductance of an inductor if the number of turns in the coil is increased?

A) The inductance increases

B) The inductance decreases

C) The inductance remains the same

D) It depends on the material of the coil

Q5. What is the inductance of an inductor that produces an induced emf of 2 volts when the current through it changes at a rate of 4 A/s?

A) 0.5 henries

B) 0.25 henries

C) 8 henries

D) 16 henries

Answer: A) 0.5 henries (L = Î”Î¦/Î”I = 2/4)

Q6. What is the inductive reactance of an inductor with an inductance of 0.1 henries at a frequency of 50 Hz?

A) 31.4 ohms

B) 5 ohms

C) 0.02 ohms

D) 0.02 henries

Answer: A) 31.4 ohms (XL = 2Ï€fL)

Q7. What is the impedance of an inductor in an AC circuit?

A) Z = R + XL, where Z is the impedance, R is the resistance, and XL is the inductive reactance

B) Z = R - XL, where Z is the impedance, R is the resistance, and XL is the inductive reactance

C) Z = R/XL, where Z is the impedance, R is the resistance, and XL is the inductive reactance

D) Z = XL/R, where Z is the impedance, R is the resistance, and XL is the inductive reactance

Answer: A) Z = R + XL, where Z is the impedance, R is the resistance, and XL is the inductive reactance

Q8. What is the time constant of an RL circuit?

A) Ï„ = R/L, where Ï„ is the time constant, R is the resistance, and L is the inductance

B) Ï„ = L/R, where Ï„ is the time constant, R is the resistance, and L is the inductance

C) Ï„ = RxL, where Ï„ is the time constant, R is the resistance, and L is the inductance

D) Ï„ = L/xR, where Ï„ is the time constant, R is the resistance, and L is the inductance

Answer: B) Ï„ = L/R, where Ï„ is the time constant, R is the resistance, and L is the inductance

Q9. What is an inductor?

A) A device that stores electrical charge

B) A device that stores electrical energy in a magnetic field

C) A device that converts electrical energy into mechanical energy

D) A device that amplifies electrical signals

Answer: B) A device that stores electrical energy in a magnetic field

Q10. What is the inductive reactance of an inductor with an inductance of 0.1 H at a frequency of 50 Hz?

Answer: A) 31.4 Î© (XL = 2Ï€fL = 2Ï€ x 50 x 0.1 = 31.4)

Q12. What happens to the inductive reactance of an inductor as the frequency of the AC source increases?

A) It decreases

B) It increases

C) It remains the same

D) It depends on the inductance of the inductor

Q13. What is the property of an inductor that opposes any change in current through it?

a) Resistance

b) Capacitance

c) Impedance

d) Inductance

Q14. Which of the following factors affects the inductance of an inductor?

a) The number of turns of wire in the coil

b) The shape and size of the coil

c) The material of the core

d) All of the above

Answer: d) All of the above

Q15. In an AC circuit, what is the phase relationship between the voltage and current in an inductor?

a) The voltage leads the current by 90 degrees

b) The voltage lags the current by 90 degrees

c) The voltage and current are in phase

d) The voltage and current are out of phase, but not by 90 degrees

Answer: b) The voltage lags the current by 90 degrees

Q16. What is the purpose of a flyback diode in a circuit with an inductor?

a) To prevent the inductor from overheating

b) To prevent the inductor from generating a high-voltage spike when the current is turned off

c) To increase the inductance of the circuit

d) To reduce the resistance of the circuit

Answer: b) To prevent the inductor from generating a high-voltage spike when the current is turned off

Q17. What is the formula for calculating the voltage across an inductor?

a) V = IR

b) V = I/C

c) V = LdI/dt

d) V = Q/C

Q18. Which of the following materials is commonly used as a core for inductors?

a) Copper

b) Aluminum

c) Iron

d) Silver

Q19. In a series circuit with an inductor and a resistor, what happens to the impedance as the frequency of the AC source increases?

a) The impedance increases

b) The impedance decreases

c) The impedance remains constant

d) It depends on the values of the inductor and resistor

Q20. What is the role of an inductor in a power supply circuit?

a) To regulate the output voltage

b) To convert AC power to DC power

c) To filter out high-frequency noise from the output

d) To provide isolation between the input and output circuits

Answer: c) To filter out high-frequency noise from the output

Q22. What is the difference between a fixed inductor and a variable inductor?

a) A fixed inductor has a fixed inductance value while a variable inductor has a variable inductance value.

b) A fixed inductor is used in DC circuits while a variable inductor is used in AC circuits.

c) A fixed inductor is made of copper wire while a variable inductor is made of silver wire.

d) A fixed inductor has a low Q-factor while a variable inductor has a high Q-factor.

Answer: a) A fixed inductor has a fixed inductance value while a variable inductor has a variable inductance value.

Q23. What is the difference between a solenoid and a coil?

a) A solenoid has a core material while a coil does not.

b) A solenoid is used to generate a magnetic field while a coil is used to store energy in the form of magnetic fields.

c) A solenoid is always a single layer coil while a coil can be either single or multiple layer.

d) A solenoid has a larger diameter compared to a coil.

Answer: a) A solenoid has a core material while a coil does not.

Q24. What is the self-resonant frequency of an inductor?

a) The frequency at which the inductor produces the highest magnetic field.

b) The frequency at which the inductor has the highest impedance.

c) The frequency at which the inductor resonates with the capacitance of the circuit.

d) The frequency at which the inductor becomes saturated with magnetic flux.

Answer: c) The frequency at which the inductor resonates with the capacitance of the circuit.

Q25. What is the skin effect in inductors?

a) The tendency of the current to concentrate at the surface of the conductor.

b) The tendency of the current to flow through the core of the inductor.

c) The tendency of the inductor to heat up when subjected to high currents.

d) The tendency of the inductor to produce high-voltage spikes when the current is turned off.

Answer: a) The tendency of the current to concentrate at the surface of the conductor.

Q26. What is the purpose of a transformer in a circuit?

a) To increase the voltage of an AC power source.

b) To decrease the voltage of an AC power source.

c) To isolate the input and output circuits.

d) To regulate the output voltage.

Answer: a) To increase the voltage of an AC power source (or decrease the voltage depending on the transformer winding ratios).

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