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## Capacitor MCQs - All Important Questions

Q1. What is a capacitor?

A) A device used to store electrical charge

B) A device used to generate electrical charge

C) A device used to measure electrical charge

D) A device used to resist electrical charge

Answer: A) A device used to store electrical charge

Q2. Which of the following is a unit of capacitance?

A) Ohm

B) Ampere

C) Coulomb

Q3. What is the formula for capacitance?

A) C = Q/V, where C is capacitance, Q is charge, and V is voltage

B) Q = CV, where Q is charge, C is capacitance, and V is voltage

C) V = IR, where V is voltage, I is current, and R is resistance

D) P = IV, where P is power, I is current, and V is voltage

Answer: A) C = Q/V, where C is capacitance, Q is charge, and V is voltage

Q4. What happens when a capacitor is connected to a voltage source?

A) It stores electrical energy and becomes charged

B) It releases electrical energy and becomes discharged

C) It generates electrical energy and becomes charged

D) It resists electrical energy and remains neutral

Answer: A) It stores electrical energy and becomes charged

Q5. What is the time constant of a capacitor?

A) The time it takes for a capacitor to charge or discharge to 63.2% of its maximum voltage

B) The time it takes for a capacitor to charge or discharge to 50% of its maximum voltage

C) The time it takes for a capacitor to charge or discharge to 75% of its maximum voltage

D) The time it takes for a capacitor to charge or discharge to 90% of its maximum voltage

Answer: A) The time it takes for a capacitor to charge or discharge to 63.2% of its maximum voltage

Q6. In an AC circuit, what happens to the capacitive reactance as the frequency increases?

A) It decreases

B) It increases

C) It remains the same

D) It depends on the capacitance of the capacitor

✅Also Check - Ohm's Law MCQ Important Questions

Q7. What happens when two capacitors are connected in parallel?

A) The equivalent capacitance is the sum of the individual capacitances

B) The equivalent capacitance is less than the smallest individual capacitance

C) The equivalent capacitance is greater than the largest individual capacitance

D) The equivalent capacitance is equal to the average of the individual capacitances

Answer: A) The equivalent capacitance is the sum of the individual capacitances

Q8. What is the impedance of a capacitor in an AC circuit?

A) Xc = 1/2Ï€fC, where Xc is the capacitive reactance, f is the frequency, and C is the capacitance

B) Xc = 2Ï€fC, where Xc is the capacitive reactance, f is the frequency, and C is the capacitance

C) Xc = Ï€fC, where Xc is the capacitive reactance, f is the frequency, and C is the capacitance

D) Xc = 1/Ï€fC, where Xc is the capacitive reactance, f is the frequency, and C is the capacitance

Answer: A) Xc = 1/2Ï€fC, where Xc is the capacitive reactance, f is the frequency, and C is the capacitance

Q9. What is the time constant of a RC circuit?

A) Ï„ = R/C, where Ï„ is the time constant, R is the resistance, and C is the capacitance

B) Ï„ = C/R, where Ï„ is the time constant, R is the resistance, and C is the capacitance

C) Ï„ = RxC, where Ï„ is the time constant, R is the resistance, and C is the capacitance

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

Answer: A) Ï„ = R/C, where Ï„ is the time constant, R is the resistance, and C is the capacitance

Q10. What is a variable capacitor?

A) A capacitor with an adjustable capacitance value

B) A capacitor that varies its voltage output

C) A capacitor that varies its current output

D) A capacitor with a fixed capacitance value

Q11. What is the role of a capacitor in a DC circuit?

A) It blocks the flow of DC current

B) It allows the flow of DC current

C) It generates DC current

D) It converts DC current to AC current

Answer: A) It blocks the flow of DC current

✅Also Check - Ohm's Law MCQ Important Questions

Q12. In a series RC circuit, what happens to the voltage across the resistor and the capacitor as the frequency of the AC source increases?

A) The voltage across the resistor increases and the voltage across the capacitor decreases

B) The voltage across the resistor decreases and the voltage across the capacitor increases

C) The voltage across both the resistor and the capacitor decrease

D) The voltage across both the resistor and the capacitor increase

Answer: A) The voltage across the resistor increases and the voltage across the capacitor decreases

Q13. What is the maximum voltage that a capacitor can withstand?

A) Its breakdown voltage

B) Its capacitance voltage

C) Its charging voltage

D) Its discharge voltage

Q14. What is the energy stored in a capacitor?

A) E = 1/2CV^2, where E is energy, C is capacitance, and V is voltage

B) E = CV^2, where E is energy, C is capacitance, and V is voltage

C) E = QV, where E is energy, Q is charge, and V is voltage

D) E = I^2R, where E is energy, I is current, and R is resistance

Answer: A) E = 1/2CV^2, where E is energy, C is capacitance, and V is voltage

Q15. What is the purpose of a decoupling capacitor in electronic circuits?

A) To filter out unwanted high-frequency noise

B) To provide a stable voltage source for the circuit

C) To prevent unwanted feedback in the circuit

D) To block the flow of DC current

Answer: B) To provide a stable voltage source for the circuit

✅Also Check - Ohm's Law MCQ Important Questions

Q16. What is the unit of capacitance?

B) Hertz

C) Joule

D) Ohm

Q17. What is the capacitance of a capacitor that stores 10 coulombs of charge at a voltage of 5 volts?

Q18. What happens to the capacitance of a capacitor if the distance between its plates is increased?

A) The capacitance decreases

B) The capacitance increases

C) The capacitance remains the same

D) It depends on the material of the plates

Q19. What is the capacitance of a parallel-plate capacitor with plates of area 0.1 m^2 and a separation of 0.01 m, with a vacuum between the plates?

A) 8.85 x 10^-14 F

B) 8.85 x 10^-12 F

C) 8.85 x 10^-10 F

D) 8.85 x 10^-8 F

Answer: B) 8.85 x 10^-12 F (C = ÎµA/d, where Îµ is the permittivity of free space, A is the area of the plates, and d is the separation between the plates)

Q20. Which of the following materials is commonly used as a dielectric in capacitors?

A) Glass

B) Ceramic

C) Air

D) All of the above

Answer: D) All of the above