NEIEP 600 FINAL EXAM PRACTICE TEST 410+ MULTIPLE
CHOICE QUESTIONS COMPLETE WITH 100% VERIFIED
ANSWERS AND DETAILED RATIONALES
Question 1
In capacitors, what is the purpose of the dielectric?
A. To increase capacitance
B. To prevent arcing within the capacitor
C. To reduce resistance
D. To store electrons
Correct Answer: B. To prevent arcing within the capacitor
Explanation: The dielectric is an insulating material between capacitor plates that
prevents arcing (current jumping between plates) while allowing electrostatic
charge storage.
Question 2
Which of the following is true about capacitors in AC circuits?
A. Voltage leads current
B. Current leads voltage all the time
C. Current and voltage are in phase
D. Current lags voltage
Correct Answer: B. Current leads voltage all the time
Explanation: In a purely capacitive AC circuit, current leads voltage by 90 degrees.
This is opposite of an inductive circuit where current lags voltage.
Question 3
What describes a capacitor's ability to store an electrical charge?
,A. Resistance
B. Inductance
C. Capacitance
D. Impedance
Correct Answer: C. Capacitance
Explanation: Capacitance (measured in farads) is the ability of a capacitor to store
an electrical charge. It is determined by plate area, distance between plates, and
dielectric material.
Question 4
Which of the following statements is correct about polarized electrolytic
capacitors?
A. Voltage polarity does not matter
B. Voltage polarity must be correct
C. They can be used in AC circuits only
D. They have no dielectric
Correct Answer: B. Voltage polarity must be correct
Explanation: Polarized electrolytic capacitors have a positive and negative
terminal. Reverse polarity can cause dielectric breakdown, overheating, and
explosion.
Question 5
What is the time constant for a circuit with 150k ohms and 2 microfarad
capacitor?
A. 0.3 seconds
B. 0.03 seconds
C. 3.0 seconds
D. 300 seconds
,Correct Answer: A. 0.3 seconds
*Explanation: Time constant (τ) = R × C = 150,000 Ω × 0.000002 F = 0.3 seconds.*
Question 6
If frequency is increased in a capacitive circuit, what will happen to capacitive
reactance?
A. Capacitive reactance will increase
B. Capacitive reactance will decrease
C. Capacitive reactance will stay the same
D. Capacitive reactance will become zero
Correct Answer: B. Capacitive reactance will decrease
*Explanation: Capacitive reactance (Xc = 1/(2πfC)) is inversely proportional to
frequency. As frequency increases, Xc decreases.*
Question 7
What happens in a DC circuit when the capacitor voltage equals the source
voltage?
A. Current flow stops in the circuit
B. Current flow is maximum
C. The capacitor is shorted
D. The capacitor discharges
Correct Answer: A. Current flow stops in the circuit
Explanation: When fully charged, capacitor voltage equals source voltage, no
potential difference exists, so current flow stops (open circuit condition).
Question 8
In a DC circuit, which is correct about capacitors the instant when power is
applied?
A. Current is zero
, B. Current is maximum
C. Voltage is maximum
D. The capacitor is fully charged
Correct Answer: B. Current is maximum
Explanation: At the instant power is applied, the capacitor acts as a short circuit
(zero voltage, maximum current). Current then decreases exponentially as the
capacitor charges.
Question 9
What is the total capacitance of three capacitors (100 µF, 100 µF, 50 µF) connected
in parallel?
A. 25 µF
B. 150 µF
C. 250 µF
D. 500 µF
Correct Answer: C. 250 µF
*Explanation: Capacitors in parallel add: Ctotal = 100 + 100 + 50 = 250 µF.*
Question 10
If a circuit has a capacitor of 5 microfarads and a source voltage of 120 volts DC
through a resistance of 200k ohms, how long will it take to fully charge?
A. 0.5 seconds
B. 1 second
C. 5 seconds
D. 10 seconds
Correct Answer: C. 5 seconds
*Explanation: One time constant τ = R × C = 200,000 Ω × 0.000005 F = 1 second. A
capacitor is considered fully charged after 5 time constants = 5 seconds.*
CHOICE QUESTIONS COMPLETE WITH 100% VERIFIED
ANSWERS AND DETAILED RATIONALES
Question 1
In capacitors, what is the purpose of the dielectric?
A. To increase capacitance
B. To prevent arcing within the capacitor
C. To reduce resistance
D. To store electrons
Correct Answer: B. To prevent arcing within the capacitor
Explanation: The dielectric is an insulating material between capacitor plates that
prevents arcing (current jumping between plates) while allowing electrostatic
charge storage.
Question 2
Which of the following is true about capacitors in AC circuits?
A. Voltage leads current
B. Current leads voltage all the time
C. Current and voltage are in phase
D. Current lags voltage
Correct Answer: B. Current leads voltage all the time
Explanation: In a purely capacitive AC circuit, current leads voltage by 90 degrees.
This is opposite of an inductive circuit where current lags voltage.
Question 3
What describes a capacitor's ability to store an electrical charge?
,A. Resistance
B. Inductance
C. Capacitance
D. Impedance
Correct Answer: C. Capacitance
Explanation: Capacitance (measured in farads) is the ability of a capacitor to store
an electrical charge. It is determined by plate area, distance between plates, and
dielectric material.
Question 4
Which of the following statements is correct about polarized electrolytic
capacitors?
A. Voltage polarity does not matter
B. Voltage polarity must be correct
C. They can be used in AC circuits only
D. They have no dielectric
Correct Answer: B. Voltage polarity must be correct
Explanation: Polarized electrolytic capacitors have a positive and negative
terminal. Reverse polarity can cause dielectric breakdown, overheating, and
explosion.
Question 5
What is the time constant for a circuit with 150k ohms and 2 microfarad
capacitor?
A. 0.3 seconds
B. 0.03 seconds
C. 3.0 seconds
D. 300 seconds
,Correct Answer: A. 0.3 seconds
*Explanation: Time constant (τ) = R × C = 150,000 Ω × 0.000002 F = 0.3 seconds.*
Question 6
If frequency is increased in a capacitive circuit, what will happen to capacitive
reactance?
A. Capacitive reactance will increase
B. Capacitive reactance will decrease
C. Capacitive reactance will stay the same
D. Capacitive reactance will become zero
Correct Answer: B. Capacitive reactance will decrease
*Explanation: Capacitive reactance (Xc = 1/(2πfC)) is inversely proportional to
frequency. As frequency increases, Xc decreases.*
Question 7
What happens in a DC circuit when the capacitor voltage equals the source
voltage?
A. Current flow stops in the circuit
B. Current flow is maximum
C. The capacitor is shorted
D. The capacitor discharges
Correct Answer: A. Current flow stops in the circuit
Explanation: When fully charged, capacitor voltage equals source voltage, no
potential difference exists, so current flow stops (open circuit condition).
Question 8
In a DC circuit, which is correct about capacitors the instant when power is
applied?
A. Current is zero
, B. Current is maximum
C. Voltage is maximum
D. The capacitor is fully charged
Correct Answer: B. Current is maximum
Explanation: At the instant power is applied, the capacitor acts as a short circuit
(zero voltage, maximum current). Current then decreases exponentially as the
capacitor charges.
Question 9
What is the total capacitance of three capacitors (100 µF, 100 µF, 50 µF) connected
in parallel?
A. 25 µF
B. 150 µF
C. 250 µF
D. 500 µF
Correct Answer: C. 250 µF
*Explanation: Capacitors in parallel add: Ctotal = 100 + 100 + 50 = 250 µF.*
Question 10
If a circuit has a capacitor of 5 microfarads and a source voltage of 120 volts DC
through a resistance of 200k ohms, how long will it take to fully charge?
A. 0.5 seconds
B. 1 second
C. 5 seconds
D. 10 seconds
Correct Answer: C. 5 seconds
*Explanation: One time constant τ = R × C = 200,000 Ω × 0.000005 F = 1 second. A
capacitor is considered fully charged after 5 time constants = 5 seconds.*
