NYC DCAS ELECTRICIAN EXAM QUESTIONS WITH
CORRECT ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A
SECTION 1: ELECTRICAL THEORY & OHM'S LAW
1. According to Ohm's Law, what is the formula for voltage?
• A) V = I / R
• B) V = I × R
• C) V = R / I
• D) V = P × I
Correct Answer: B
Rationale: Ohm's Law states that voltage equals current multiplied by resistance
(V = I × R). Option A calculates current, option C inverts the relationship, and
option D is a power formula (P = V × I).
2. A 240V single-phase circuit supplies a 4800W electric water heater. What is
the current draw?
• A) 15A
• B) 20A
• C) 25A
• D) 30A
Correct Answer: B
Rationale: Using the power formula P = V × I, rearrange to I = P ÷ V = 4800W ÷
,240V = 20 amperes. Per NEC 422.11(E), storage-type water heaters are considered
continuous loads, requiring conductors rated at 125% (25A).
3. What is the unit of electrical resistance?
• A) Volt
• B) Ampere
• C) Ohm
• D) Watt
Correct Answer: C
Rationale: The ohm (Ω) is the SI unit of electrical resistance. Volts measure voltage,
amperes measure current, and watts measure power.
4. A 10Ω resistor carries 2A current. What is the voltage across it?
• A) 5V
• B) 12V
• C) 18V
• D) 20V
Correct Answer: D
Rationale: Using Ohm's Law, V = I × R = 2A × 10Ω = 20 volts.
5. Which law defines the relationship between voltage, current, and resistance?
• A) Kirchhoff's Law
• B) Ohm's Law
• C) Faraday's Law
, • D) Newton's Law
Correct Answer: B
Rationale: Ohm's Law states that voltage equals current multiplied by resistance
(V = IR). Kirchhoff's Law addresses current and voltage in circuits; Faraday's Law
relates to electromagnetic induction; Newton's Law applies to motion.
6. What is the unit of electrical power?
• A) Volt
• B) Ampere
• C) Watt
• D) Ohm
Correct Answer: C
Rationale: The watt (W) is the SI unit of electrical power, representing the rate of
energy transfer. Voltage is measured in volts, current in amperes, and resistance in
ohms.
7. What is the correct formula for calculating electrical power (P) in a DC circuit?
• A) P = I × R
• B) P = V × I
• C) P = V² / R
• D) Both B and C
Correct Answer: D
Rationale: Power in DC circuits can be calculated using P = V × I (voltage times
current) or, by substituting Ohm's Law, P = V² / R or P = I² × R. Option A (P = I × R)
calculates voltage, not power.
, 8. What does "power factor" describe in an AC system?
• A) The ratio of true power to apparent power
• B) The ratio of voltage to current
• C) The relationship of volts and ohms
• D) The product of voltage and current
Correct Answer: A
Rationale: Power factor = True Power (watts) / Apparent Power (volt-amperes).
Low PF indicates reactive loads like motors and transformers.
9. Resistance increases when wire length:
• A) Decreases
• B) Increases
• C) Stays the same
• D) Becomes zero
Correct Answer: B
Rationale: Resistance is directly proportional to the length of a conductor (R =
ρL/A). Doubling the length doubles the resistance. Larger conductor diameter
decreases resistance.
10. A transformer operates at 95% efficiency. If output is 9.5 kW, what is the
input power?
• A) 9.0 kW
• B) 9.5 kW
• C) 10.0 kW
• D) 10.5 kW
CORRECT ANSWERS (VERIFIED ANSWERS) PLUS
RATIONALES 2026 Q&A
SECTION 1: ELECTRICAL THEORY & OHM'S LAW
1. According to Ohm's Law, what is the formula for voltage?
• A) V = I / R
• B) V = I × R
• C) V = R / I
• D) V = P × I
Correct Answer: B
Rationale: Ohm's Law states that voltage equals current multiplied by resistance
(V = I × R). Option A calculates current, option C inverts the relationship, and
option D is a power formula (P = V × I).
2. A 240V single-phase circuit supplies a 4800W electric water heater. What is
the current draw?
• A) 15A
• B) 20A
• C) 25A
• D) 30A
Correct Answer: B
Rationale: Using the power formula P = V × I, rearrange to I = P ÷ V = 4800W ÷
,240V = 20 amperes. Per NEC 422.11(E), storage-type water heaters are considered
continuous loads, requiring conductors rated at 125% (25A).
3. What is the unit of electrical resistance?
• A) Volt
• B) Ampere
• C) Ohm
• D) Watt
Correct Answer: C
Rationale: The ohm (Ω) is the SI unit of electrical resistance. Volts measure voltage,
amperes measure current, and watts measure power.
4. A 10Ω resistor carries 2A current. What is the voltage across it?
• A) 5V
• B) 12V
• C) 18V
• D) 20V
Correct Answer: D
Rationale: Using Ohm's Law, V = I × R = 2A × 10Ω = 20 volts.
5. Which law defines the relationship between voltage, current, and resistance?
• A) Kirchhoff's Law
• B) Ohm's Law
• C) Faraday's Law
, • D) Newton's Law
Correct Answer: B
Rationale: Ohm's Law states that voltage equals current multiplied by resistance
(V = IR). Kirchhoff's Law addresses current and voltage in circuits; Faraday's Law
relates to electromagnetic induction; Newton's Law applies to motion.
6. What is the unit of electrical power?
• A) Volt
• B) Ampere
• C) Watt
• D) Ohm
Correct Answer: C
Rationale: The watt (W) is the SI unit of electrical power, representing the rate of
energy transfer. Voltage is measured in volts, current in amperes, and resistance in
ohms.
7. What is the correct formula for calculating electrical power (P) in a DC circuit?
• A) P = I × R
• B) P = V × I
• C) P = V² / R
• D) Both B and C
Correct Answer: D
Rationale: Power in DC circuits can be calculated using P = V × I (voltage times
current) or, by substituting Ohm's Law, P = V² / R or P = I² × R. Option A (P = I × R)
calculates voltage, not power.
, 8. What does "power factor" describe in an AC system?
• A) The ratio of true power to apparent power
• B) The ratio of voltage to current
• C) The relationship of volts and ohms
• D) The product of voltage and current
Correct Answer: A
Rationale: Power factor = True Power (watts) / Apparent Power (volt-amperes).
Low PF indicates reactive loads like motors and transformers.
9. Resistance increases when wire length:
• A) Decreases
• B) Increases
• C) Stays the same
• D) Becomes zero
Correct Answer: B
Rationale: Resistance is directly proportional to the length of a conductor (R =
ρL/A). Doubling the length doubles the resistance. Larger conductor diameter
decreases resistance.
10. A transformer operates at 95% efficiency. If output is 9.5 kW, what is the
input power?
• A) 9.0 kW
• B) 9.5 kW
• C) 10.0 kW
• D) 10.5 kW
