,LADWP Electrical Mechanic–Test Technician Exam Bundle
Verified Questions and Answers | 2025/2026 Exam Prep |
Complete Study Resource for Success
SECTION 1: ELECTRICAL THEORY & MATHEMATICS (Q1–Q30)
Question 1
A 120V circuit draws 15A. What is the resistance?
A) 4Ω
B) 8Ω
C) 12Ω
D) 16Ω
Correct Answer: B
Rationale: Ohm's Law states R = V / I = = 8Ω. This fundamental relationship is essential for
electrical troubleshooting.
Question 2
What is the formula for electrical power in watts?
A) P = I² / R
B) P = V × I
C) P = V / I
D) P = R × I
Correct Answer: 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 and represents the rate at which electrical energy is converted to another
form of energy.
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
Correct Answer: 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?
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
Correct Answer: B
Rationale: In a purely inductive circuit, current lags voltage by 90°. This is due to the inductor's
opposition to changes in current.
Question 5
What is the SI unit of electrical charge, equal to the quantity of electricity conveyed in one second by a
current of one ampere?
A) Ohm
B) Volt
C) Coulomb
D) Watt
Correct Answer: C
Rationale: The coulomb (C) is the fundamental unit of electric charge. One coulomb is defined as the
charge transported by a steady current of one ampere flowing for one second.
Question 6
A bolt is specified as 1/4-28. What does the "28" indicate?
A) The tensile strength in ksi
B) The length in millimeters
C) The number of threads per inch
D) The wrench size required
Correct Answer: C
, Rationale: In bolt specifications, the number following the dash indicates the thread pitch. "1/4-28"
means a diameter of 1/4 inch with 28 threads per inch (TPI).
Question 7
Of the following electrical devices, which is NOT normally used in direct current (DC) electrical circuits?
A) Circuit breaker
B) Double-pole switch
C) Transformer
D) Inverter
Correct Answer: C
Rationale: Transformers rely on electromagnetic induction, which requires a changing magnetic field. A
DC supply is unidirectional and provides a constant magnetic field, so a transformer will not function on
DC and may burn out.
Question 8
What instrument is used to measure the insulation resistance of a rubber-covered cable?
A) Ammeter
B) Wattmeter
C) Megger (Insulation Resistance Tester)
D) Oscilloscope
Correct Answer: C
Rationale: A Megger applies a high DC voltage (e.g., 500V or 1000V) to measure resistance in megohms,
thereby determining the integrity of cable insulation.
Question 9
In a three-phase Y-connected (Wye) AC power system, the voltage from any one leg to ground is 120V.
What is the voltage between each pair of hot legs?
A) 120V
B) 208V
C) 240V
D) 277V
Correct Answer: B
Rationale: In a Wye configuration, line voltage is equal to phase voltage multiplied by the square root of
3 (120V × √3 ≈ 208V).
Verified Questions and Answers | 2025/2026 Exam Prep |
Complete Study Resource for Success
SECTION 1: ELECTRICAL THEORY & MATHEMATICS (Q1–Q30)
Question 1
A 120V circuit draws 15A. What is the resistance?
A) 4Ω
B) 8Ω
C) 12Ω
D) 16Ω
Correct Answer: B
Rationale: Ohm's Law states R = V / I = = 8Ω. This fundamental relationship is essential for
electrical troubleshooting.
Question 2
What is the formula for electrical power in watts?
A) P = I² / R
B) P = V × I
C) P = V / I
D) P = R × I
Correct Answer: 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 and represents the rate at which electrical energy is converted to another
form of energy.
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
Correct Answer: 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?
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
Correct Answer: B
Rationale: In a purely inductive circuit, current lags voltage by 90°. This is due to the inductor's
opposition to changes in current.
Question 5
What is the SI unit of electrical charge, equal to the quantity of electricity conveyed in one second by a
current of one ampere?
A) Ohm
B) Volt
C) Coulomb
D) Watt
Correct Answer: C
Rationale: The coulomb (C) is the fundamental unit of electric charge. One coulomb is defined as the
charge transported by a steady current of one ampere flowing for one second.
Question 6
A bolt is specified as 1/4-28. What does the "28" indicate?
A) The tensile strength in ksi
B) The length in millimeters
C) The number of threads per inch
D) The wrench size required
Correct Answer: C
, Rationale: In bolt specifications, the number following the dash indicates the thread pitch. "1/4-28"
means a diameter of 1/4 inch with 28 threads per inch (TPI).
Question 7
Of the following electrical devices, which is NOT normally used in direct current (DC) electrical circuits?
A) Circuit breaker
B) Double-pole switch
C) Transformer
D) Inverter
Correct Answer: C
Rationale: Transformers rely on electromagnetic induction, which requires a changing magnetic field. A
DC supply is unidirectional and provides a constant magnetic field, so a transformer will not function on
DC and may burn out.
Question 8
What instrument is used to measure the insulation resistance of a rubber-covered cable?
A) Ammeter
B) Wattmeter
C) Megger (Insulation Resistance Tester)
D) Oscilloscope
Correct Answer: C
Rationale: A Megger applies a high DC voltage (e.g., 500V or 1000V) to measure resistance in megohms,
thereby determining the integrity of cable insulation.
Question 9
In a three-phase Y-connected (Wye) AC power system, the voltage from any one leg to ground is 120V.
What is the voltage between each pair of hot legs?
A) 120V
B) 208V
C) 240V
D) 277V
Correct Answer: B
Rationale: In a Wye configuration, line voltage is equal to phase voltage multiplied by the square root of
3 (120V × √3 ≈ 208V).
