LADWP ELECTRICAL MECHANIC–TEST
TECHNICIAN: 200 PRACTICE QUESTIONS &
VERIFIED ANSWERS PLUS RATIONALES
100 % CORRECT | LATEST 2026/2027 |
ALREADY GRADED A+
📝 LADWP Electrical Mechanic–Test Technician: Practice
Questions 1-50
1. 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
Answer: C) Coulomb
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 .
2. 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
Answer: C) The number of threads per inch
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) .
3. 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
Answer: C) Transformer
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 .
4. 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
Answer: C) Megger (Insulation Resistance Tester)
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 .
5. What is the standard color for the "Neutral" wire in a 120V US residential
branch circuit?
• A) Black
• B) White
• C) Green
• D) Red
Answer: B) White
Rationale: Per the National Electrical Code (NEC), white or gray is designated for the
grounded (neutral) conductor .
6. 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
Answer: B) 208V
Rationale: In a Wye configuration, line voltage is equal to phase voltage multiplied by
the square root of 3 (120V × √3 ≈ 208V) .
7. Which of the following motors does NOT contain brushes?
, • A) DC Shunt
• B) DC Series
• C) Squirrel Cage Induction
• D) Universal Motor
Answer: C) Squirrel Cage Induction
Rationale: The squirrel cage induction motor is a brushless AC motor. Its rotor consists
of conductive bars shorted by end rings, requiring no physical contact for
commutation .
8. Which material is most commonly used as an electric heating element?
• A) Copper
• B) Aluminum
• C) Nichrome
• D) Silver
Answer: C) Nichrome
Rationale: Nichrome (an alloy of Nickel and Chromium) has high resistivity and forms
a protective oxide layer when heated, preventing it from burning out quickly .
9. The difference in electrical potential between two points is called:
• A) Current
• B) Voltage (Potential Difference)
• C) Resistance
• D) Power
Answer: B) Voltage (Potential Difference)
Rationale: Voltage is the electrical "pressure" that pushes electrons. It is always
measured as a difference in potential between two points .
10. The opposition to the flow of electrons is measured in:
• A) Amperes
• B) Volts
• C) Ohms (Ω)
• D) Watts
Answer: C) Ohms (Ω)
Rationale: Resistance, measured in ohms, quantifies how much a material opposes the
flow of electric current .
11. What is the unit of measure for "Apparent Power"?
• A) Watts (W)
, • B) Vars (VAR)
• C) Volt-Amps (VA)
• D) Joules (J)
Answer: C) Volt-Amps (VA)
Rationale: Apparent power is the product of RMS voltage and RMS current without
considering the phase angle and is measured in Volt-Amps .
12. Which logic gate produces a HIGH output only if all of its inputs are HIGH?
• A) AND gate
• B) OR gate
• C) NOT gate
• D) NAND gate
Answer: A) AND gate
Rationale: An AND gate's output is true (HIGH) only when all its inputs are true
(HIGH) .
13. A diode is an electronic component that:
• A) Amplifies a signal.
• B) Acts as a variable capacitor.
• C) Allows current to flow in only one direction.
• D) Increases the resistance as temperature rises.
Answer: C) Allows current to flow in only one direction
Rationale: Diodes act as "one-way valves" for electricity, commonly used in rectification
(converting AC to DC) .
14. When connecting an ammeter into a circuit to measure current, how must it
be connected?
• A) In series with the load.
• B) In parallel with the load.
• C) Across the power source terminals.
• D) To the ground bus only.
Answer: A) In series with the load
Rationale: An ammeter must have the full circuit current flow through it to measure it.
Connecting it in parallel would cause a short circuit due to the meter’s low internal
resistance .
15. Which instrument is used to measure the rotational speed of a motor shaft?
• A) Hydrometer
TECHNICIAN: 200 PRACTICE QUESTIONS &
VERIFIED ANSWERS PLUS RATIONALES
100 % CORRECT | LATEST 2026/2027 |
ALREADY GRADED A+
📝 LADWP Electrical Mechanic–Test Technician: Practice
Questions 1-50
1. 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
Answer: C) Coulomb
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 .
2. 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
Answer: C) The number of threads per inch
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) .
3. 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
Answer: C) Transformer
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 .
4. 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
Answer: C) Megger (Insulation Resistance Tester)
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 .
5. What is the standard color for the "Neutral" wire in a 120V US residential
branch circuit?
• A) Black
• B) White
• C) Green
• D) Red
Answer: B) White
Rationale: Per the National Electrical Code (NEC), white or gray is designated for the
grounded (neutral) conductor .
6. 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
Answer: B) 208V
Rationale: In a Wye configuration, line voltage is equal to phase voltage multiplied by
the square root of 3 (120V × √3 ≈ 208V) .
7. Which of the following motors does NOT contain brushes?
, • A) DC Shunt
• B) DC Series
• C) Squirrel Cage Induction
• D) Universal Motor
Answer: C) Squirrel Cage Induction
Rationale: The squirrel cage induction motor is a brushless AC motor. Its rotor consists
of conductive bars shorted by end rings, requiring no physical contact for
commutation .
8. Which material is most commonly used as an electric heating element?
• A) Copper
• B) Aluminum
• C) Nichrome
• D) Silver
Answer: C) Nichrome
Rationale: Nichrome (an alloy of Nickel and Chromium) has high resistivity and forms
a protective oxide layer when heated, preventing it from burning out quickly .
9. The difference in electrical potential between two points is called:
• A) Current
• B) Voltage (Potential Difference)
• C) Resistance
• D) Power
Answer: B) Voltage (Potential Difference)
Rationale: Voltage is the electrical "pressure" that pushes electrons. It is always
measured as a difference in potential between two points .
10. The opposition to the flow of electrons is measured in:
• A) Amperes
• B) Volts
• C) Ohms (Ω)
• D) Watts
Answer: C) Ohms (Ω)
Rationale: Resistance, measured in ohms, quantifies how much a material opposes the
flow of electric current .
11. What is the unit of measure for "Apparent Power"?
• A) Watts (W)
, • B) Vars (VAR)
• C) Volt-Amps (VA)
• D) Joules (J)
Answer: C) Volt-Amps (VA)
Rationale: Apparent power is the product of RMS voltage and RMS current without
considering the phase angle and is measured in Volt-Amps .
12. Which logic gate produces a HIGH output only if all of its inputs are HIGH?
• A) AND gate
• B) OR gate
• C) NOT gate
• D) NAND gate
Answer: A) AND gate
Rationale: An AND gate's output is true (HIGH) only when all its inputs are true
(HIGH) .
13. A diode is an electronic component that:
• A) Amplifies a signal.
• B) Acts as a variable capacitor.
• C) Allows current to flow in only one direction.
• D) Increases the resistance as temperature rises.
Answer: C) Allows current to flow in only one direction
Rationale: Diodes act as "one-way valves" for electricity, commonly used in rectification
(converting AC to DC) .
14. When connecting an ammeter into a circuit to measure current, how must it
be connected?
• A) In series with the load.
• B) In parallel with the load.
• C) Across the power source terminals.
• D) To the ground bus only.
Answer: A) In series with the load
Rationale: An ammeter must have the full circuit current flow through it to measure it.
Connecting it in parallel would cause a short circuit due to the meter’s low internal
resistance .
15. Which instrument is used to measure the rotational speed of a motor shaft?
• A) Hydrometer
