NYC ELECTRICIAN (DCAS) CIVIL SERVICE EXAM QUESTIONS
WITH VERIFIED SOLUTIONS - UPDATED VERSION -
COMPREHENSIVE REVIEW
1. According to Ohm's Law, what is the current in a 120V circuit with
a resistance of 24Ω?
• A) 2A
• B) 5A
• C) 10A
• D) 20A
• ANSWER : B) 5A (I = V/R = 120/24 = 5A)
2. What is the total resistance of three 6Ω resistors connected in
series?
• A) 2Ω
• B) 6Ω
• C) 12Ω
• D) 18Ω
• ANSWER : D) 18Ω (R_total = 6+6+6 = 18Ω)
3. What is the total resistance of two 8Ω resistors connected in
parallel?
• A) 16Ω
• B) 8Ω
• C) 4Ω
• D) 2Ω
• ANSWER : C) 4Ω (1/R_total = 1/8 + 1/8 = 2/8 = 1/4)
,4. In a DC circuit, power is calculated as:
• A) P = I × R
• B) P = V × I
• C) P = R² × I
• D) P = V ÷ R
• ANSWER : B) P = V × I
5. What is the standard residential voltage in New York City?
• A) 110V
• B) 120/240V
• C) 208V
• D) 277/480V
• ANSWER : B) 120/240V
6. What does "AC" stand for in electrical systems?
• A) Alternating Current
• B) Ampere Current
• C) Active Circuit
• D) Alternating Circuit
• ANSWER : A) Alternating Current
7. What is the frequency of standard AC power in the United States?
• A) 50 Hz
• B) 60 Hz
• C) 120 Hz
• D) 240 Hz
• ANSWER : B) 60 Hz
8. What is the RMS value of a 170V peak sine wave?
• A) 170V
• B) 120V
, • C) 240V
• D) 85V
• ANSWER : B) 120V (V_rms = V_peak / √2 ≈ 170/1.414 ≈ 120V)
9. In a purely resistive AC circuit, the power factor is:
• A) 0
• B) 0.5
• C) 1.0
• D) -1.0
• ANSWER : C) 1.0
10. What unit measures electrical resistance?
• A) Ampere
• B) Volt
• C) Ohm
• D) Watt
• ANSWER : C) Ohm
11. What is the formula for calculating total resistance in a parallel
circuit?
• A) R_total = R1 + R2 + R3
• B) 1/R_total = 1/R1 + 1/R2 + 1/R3
• C) R_total = R1 × R2 × R3
• D) R_total = (R1 + R2) / R3
• ANSWER : B) 1/R_total = 1/R1 + 1/R2 + 1/R3
12. Kirchhoff's Voltage Law states that:
• A) The sum of currents entering a junction equals the sum leaving
• B) The sum of voltage drops around a closed loop equals zero
• C) Voltage is directly proportional to current
• D) Power equals voltage times current
, • ANSWER : B) The sum of voltage drops around a closed loop
equals zero
13. Kirchhoff's Current Law states that:
• A) Current is inversely proportional to resistance
• B) The algebraic sum of currents at a node is zero
• C) Voltage drop equals current times resistance
• D) Power is conserved in all circuits
• ANSWER : B) The algebraic sum of currents at a node is zero
14. What is the capacitive reactance (Xc) of a 10µF capacitor at 60
Hz?
• A) 265Ω
• B) 377Ω
• C) 159Ω
• D) 1061Ω
• ANSWER : A) 265Ω (Xc = 1/(2πfC) = 1/(2π×60×10×10⁻⁶) ≈ 265Ω)
15. What is the inductive reactance (XL) of a 0.5H inductor at 60 Hz?
• A) 30Ω
• B) 188Ω
• C) 377Ω
• D) 60Ω
• ANSWER : B) 188Ω (XL = 2πfL = 2π×60×0.5 ≈ 188Ω)
16. In an AC circuit, the phase angle between voltage and current in a
purely capacitive circuit is:
• A) 0°
• B) 45°
• C) 90° (current leads voltage)
• D) 90° (current lags voltage)
• ANSWER : C) 90° (current leads voltage)
WITH VERIFIED SOLUTIONS - UPDATED VERSION -
COMPREHENSIVE REVIEW
1. According to Ohm's Law, what is the current in a 120V circuit with
a resistance of 24Ω?
• A) 2A
• B) 5A
• C) 10A
• D) 20A
• ANSWER : B) 5A (I = V/R = 120/24 = 5A)
2. What is the total resistance of three 6Ω resistors connected in
series?
• A) 2Ω
• B) 6Ω
• C) 12Ω
• D) 18Ω
• ANSWER : D) 18Ω (R_total = 6+6+6 = 18Ω)
3. What is the total resistance of two 8Ω resistors connected in
parallel?
• A) 16Ω
• B) 8Ω
• C) 4Ω
• D) 2Ω
• ANSWER : C) 4Ω (1/R_total = 1/8 + 1/8 = 2/8 = 1/4)
,4. In a DC circuit, power is calculated as:
• A) P = I × R
• B) P = V × I
• C) P = R² × I
• D) P = V ÷ R
• ANSWER : B) P = V × I
5. What is the standard residential voltage in New York City?
• A) 110V
• B) 120/240V
• C) 208V
• D) 277/480V
• ANSWER : B) 120/240V
6. What does "AC" stand for in electrical systems?
• A) Alternating Current
• B) Ampere Current
• C) Active Circuit
• D) Alternating Circuit
• ANSWER : A) Alternating Current
7. What is the frequency of standard AC power in the United States?
• A) 50 Hz
• B) 60 Hz
• C) 120 Hz
• D) 240 Hz
• ANSWER : B) 60 Hz
8. What is the RMS value of a 170V peak sine wave?
• A) 170V
• B) 120V
, • C) 240V
• D) 85V
• ANSWER : B) 120V (V_rms = V_peak / √2 ≈ 170/1.414 ≈ 120V)
9. In a purely resistive AC circuit, the power factor is:
• A) 0
• B) 0.5
• C) 1.0
• D) -1.0
• ANSWER : C) 1.0
10. What unit measures electrical resistance?
• A) Ampere
• B) Volt
• C) Ohm
• D) Watt
• ANSWER : C) Ohm
11. What is the formula for calculating total resistance in a parallel
circuit?
• A) R_total = R1 + R2 + R3
• B) 1/R_total = 1/R1 + 1/R2 + 1/R3
• C) R_total = R1 × R2 × R3
• D) R_total = (R1 + R2) / R3
• ANSWER : B) 1/R_total = 1/R1 + 1/R2 + 1/R3
12. Kirchhoff's Voltage Law states that:
• A) The sum of currents entering a junction equals the sum leaving
• B) The sum of voltage drops around a closed loop equals zero
• C) Voltage is directly proportional to current
• D) Power equals voltage times current
, • ANSWER : B) The sum of voltage drops around a closed loop
equals zero
13. Kirchhoff's Current Law states that:
• A) Current is inversely proportional to resistance
• B) The algebraic sum of currents at a node is zero
• C) Voltage drop equals current times resistance
• D) Power is conserved in all circuits
• ANSWER : B) The algebraic sum of currents at a node is zero
14. What is the capacitive reactance (Xc) of a 10µF capacitor at 60
Hz?
• A) 265Ω
• B) 377Ω
• C) 159Ω
• D) 1061Ω
• ANSWER : A) 265Ω (Xc = 1/(2πfC) = 1/(2π×60×10×10⁻⁶) ≈ 265Ω)
15. What is the inductive reactance (XL) of a 0.5H inductor at 60 Hz?
• A) 30Ω
• B) 188Ω
• C) 377Ω
• D) 60Ω
• ANSWER : B) 188Ω (XL = 2πfL = 2π×60×0.5 ≈ 188Ω)
16. In an AC circuit, the phase angle between voltage and current in a
purely capacitive circuit is:
• A) 0°
• B) 45°
• C) 90° (current leads voltage)
• D) 90° (current lags voltage)
• ANSWER : C) 90° (current leads voltage)
