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
D) Farad
Answer: D) Farad
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
Answer: A) It decreases
✅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 = πfC, 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
Answer: A) A capacitor with an adjustable 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
Answer: A) Its breakdown 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?
A) Farad
B) Hertz
C) Joule
D) Ohm
Answer: A) Farad
Q17. What is the capacitance of a capacitor that stores 10 coulombs of charge at a voltage of 5 volts?
A) 2 Farads
B) 50 Farads
C) 0.5 Farads
D) 0.2 Farads
Answer: C) 0.5 Farads (C = Q/V = 10/5)
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
Answer: A) The capacitance decreases
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 = εA/d, where ε 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
