1
LADWP Electrical Mechanic-Test Technician
Practice Exam 2026 Edition: 200 Multiple
Choice Questions with Verified Answers and
Detailed Rationales for Los Angeles
Department of Water and Power Certification
Success || Graded A+
SECTION 1: ELECTRICAL THEORY AND MATHEMATICS (Questions 1–40)
Question 1
A 120V circuit draws 15A. What is the resistance?
A) 4Ω
B) 8Ω
C) 12Ω
D) 16Ω
ANS: B
Rationale: Ohm's Law states R = V/I = 120/15 = 8Ω. This fundamental relationship
is essential for electrical troubleshooting .
Question 2
What is the formula for electrical power in watts?
, 2
A) P = I²/R
B) P = V × I
C) P = V/I
D) P = R × I
ANS: B
Rationale: The formula for electrical power is P = V × I. It can also be expressed as
P = I² × R or P = V²/R. Power is measured in watts .
Question 3
Total resistance in a series circuit is calculated as:
A) R_T = R1 + R2 + R3
B) R_T = 1/R1 + 1/R2 + 1/R3
C) R_T = R1 × R2 / (R1 + R2)
D) R_T = R1 - R2 - R3
ANS: A
Rationale: In a series circuit, total resistance equals the sum of all individual
resistances. This is a fundamental law of series circuits .
Question 4
In a purely inductive AC circuit, how does current relate to voltage?
, 3
A) Current leads voltage by 90°
B) Current lags voltage by 90°
C) Current is in phase with voltage
D) Current is 180° out of phase with voltage
ANS: B
Rationale: In a purely inductive circuit, current lags voltage by 90° because the
inductor opposes changes in current .
Question 5
In a purely capacitive AC circuit, how does current relate to voltage?
A) Current leads voltage by 90°
B) Current lags voltage by 90°
C) Current is in phase with voltage
D) Current is 180° out of phase with voltage
ANS: A
Rationale: In a purely capacitive circuit, current leads voltage by 90° because the
capacitor opposes changes in voltage .
Question 6
What is the primary function of a capacitor in an AC circuit?
, 4
A) To store energy in a magnetic field
B) To oppose changes in voltage
C) To oppose changes in current
D) To convert AC to DC
ANS: B
Rationale: Capacitors resist voltage change; inductors resist current change .
Question 7
What is the primary purpose of a "Megger" (Insulation Resistance Tester)?
A) Measure high current flow
B) Measure low resistance in windings (0.1 ohms)
C) Measure high resistance in insulation (Megaohms)
D) Measure capacitance coupling
ANS: C
Rationale: A Megger applies a high DC voltage (500V, 1000V, 5kV) to measure
insulation resistance, ensuring it is not degraded .
Question 8
A transformer has a turns ratio of 10:1 (Primary:Secondary). If 2,400V AC is
applied to the primary, what is the secondary voltage?
LADWP Electrical Mechanic-Test Technician
Practice Exam 2026 Edition: 200 Multiple
Choice Questions with Verified Answers and
Detailed Rationales for Los Angeles
Department of Water and Power Certification
Success || Graded A+
SECTION 1: ELECTRICAL THEORY AND MATHEMATICS (Questions 1–40)
Question 1
A 120V circuit draws 15A. What is the resistance?
A) 4Ω
B) 8Ω
C) 12Ω
D) 16Ω
ANS: B
Rationale: Ohm's Law states R = V/I = 120/15 = 8Ω. This fundamental relationship
is essential for electrical troubleshooting .
Question 2
What is the formula for electrical power in watts?
, 2
A) P = I²/R
B) P = V × I
C) P = V/I
D) P = R × I
ANS: B
Rationale: The formula for electrical power is P = V × I. It can also be expressed as
P = I² × R or P = V²/R. Power is measured in watts .
Question 3
Total resistance in a series circuit is calculated as:
A) R_T = R1 + R2 + R3
B) R_T = 1/R1 + 1/R2 + 1/R3
C) R_T = R1 × R2 / (R1 + R2)
D) R_T = R1 - R2 - R3
ANS: A
Rationale: In a series circuit, total resistance equals the sum of all individual
resistances. This is a fundamental law of series circuits .
Question 4
In a purely inductive AC circuit, how does current relate to voltage?
, 3
A) Current leads voltage by 90°
B) Current lags voltage by 90°
C) Current is in phase with voltage
D) Current is 180° out of phase with voltage
ANS: B
Rationale: In a purely inductive circuit, current lags voltage by 90° because the
inductor opposes changes in current .
Question 5
In a purely capacitive AC circuit, how does current relate to voltage?
A) Current leads voltage by 90°
B) Current lags voltage by 90°
C) Current is in phase with voltage
D) Current is 180° out of phase with voltage
ANS: A
Rationale: In a purely capacitive circuit, current leads voltage by 90° because the
capacitor opposes changes in voltage .
Question 6
What is the primary function of a capacitor in an AC circuit?
, 4
A) To store energy in a magnetic field
B) To oppose changes in voltage
C) To oppose changes in current
D) To convert AC to DC
ANS: B
Rationale: Capacitors resist voltage change; inductors resist current change .
Question 7
What is the primary purpose of a "Megger" (Insulation Resistance Tester)?
A) Measure high current flow
B) Measure low resistance in windings (0.1 ohms)
C) Measure high resistance in insulation (Megaohms)
D) Measure capacitance coupling
ANS: C
Rationale: A Megger applies a high DC voltage (500V, 1000V, 5kV) to measure
insulation resistance, ensuring it is not degraded .
Question 8
A transformer has a turns ratio of 10:1 (Primary:Secondary). If 2,400V AC is
applied to the primary, what is the secondary voltage?
