LADWP Electrical Mechanic–Test
Technician Exam with verified
answers and rationale 2026\2027
instant pdf
section 1: Electrical Theory & Fundamentals (Questions 1-
25)
Q1. A circuit has a resistance of 12 ohms and is supplied by 120 volts. What is
the current flow?
• A) 5A
• B) 8A
• C) 10A
• D) 14A
Answer: C) 10A
Rationale: Ohm's Law states I = V / R. 120V ÷ 12Ω = 10 amperes. This is a
fundamental calculation that forms the basis of all circuit analysis .
Q2. A 240-volt circuit supplies a 20-amp load. What is the power consumed?
• A) 1,200W
• B) 2,400W
• C) 4,800W
• D) 6,000W
Answer: C) 4,800W
Rationale: Power formula P = V × I. 240V × 20A = 4,800 watts. This represents the true
power consumed by the load .
,Q3. What is the total resistance of two 10-ohm resistors connected in parallel?
• A) 5Ω
• B) 10Ω
• C) 15Ω
• D) 20Ω
Answer: A) 5Ω
Rationale: Parallel resistance formula: R_T = 1 / (1/R₁ + 1/R₂). R_T = 1 / (1/10 + 1/10)
= 5Ω. Parallel connections always result in lower total resistance than the smallest
individual resistor .
Q4. What happens to total current in a parallel circuit as additional branches are
added?
• A) It decreases
• B) It remains constant
• C) It increases
• D) It becomes zero
Answer: C) It increases
Rationale: Adding branches reduces total resistance, which increases total current
according to Ohm's Law. Each new branch provides an additional path for current
flow .
Q5. The difference in electrical potential between two points is called:
• A) Current
• B) Voltage (Potential Difference)
• C) Resistance
• D) Power
Answer: B) Voltage
Rationale: Voltage is the electrical "pressure" that pushes electrons through a circuit. It
is always measured as a difference between two points .
,Q6. 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) Coulomb
• C) Watt
• D) Henry
Answer: B) Coulomb
Rationale: 1 Ampere = 1 Coulomb per second. The Coulomb is the fundamental unit of
electric charge .
Q7. 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 (√3). 120V × √3 ≈ 208V. This is the standard 120/208V three-
phase system .
Q8. In a balanced 3-phase Wye system, what is the relationship between line
current and phase current?
• A) I_L = √3 × I_phase
• B) I_L = I_phase
• C) I_L = I_phase / √3
• D) I_L = 2 × I_phase
Answer: B) I_L = I_phase
, Rationale: In a Wye connection, line current equals phase current because there is only
one path per phase. The current flows through the line and then through the phase
winding .
Q9. In a balanced 3-phase Delta system, what is the relationship between line
current and phase current?
• A) I_L = I_phase
• B) I_L = √3 × I_phase
• C) I_L = I_phase / √3
• D) I_L = 2 × I_phase
Answer: B) I_L = √3 × I_phase
Rationale: In a Delta connection, line current is √3 times the phase current because the
line current splits between two phase windings .
Q10. What is the formula for three-phase power?
• A) P = V × I
• B) P = I² × R
• C) P = √3 × V_L × I_L × PF
• D) P = V² / R
Answer: C) P = √3 × V_L × I_L × PF
Rationale: Three-phase power is calculated using the line voltage, line current, and
power factor. The √3 factor accounts for the phase relationships in a three-phase
system .
Q11. What is the "Power Factor" of a purely resistive circuit?
• A) 0
• B) 0.5
• C) 0.707
• D) 1.0
Technician Exam with verified
answers and rationale 2026\2027
instant pdf
section 1: Electrical Theory & Fundamentals (Questions 1-
25)
Q1. A circuit has a resistance of 12 ohms and is supplied by 120 volts. What is
the current flow?
• A) 5A
• B) 8A
• C) 10A
• D) 14A
Answer: C) 10A
Rationale: Ohm's Law states I = V / R. 120V ÷ 12Ω = 10 amperes. This is a
fundamental calculation that forms the basis of all circuit analysis .
Q2. A 240-volt circuit supplies a 20-amp load. What is the power consumed?
• A) 1,200W
• B) 2,400W
• C) 4,800W
• D) 6,000W
Answer: C) 4,800W
Rationale: Power formula P = V × I. 240V × 20A = 4,800 watts. This represents the true
power consumed by the load .
,Q3. What is the total resistance of two 10-ohm resistors connected in parallel?
• A) 5Ω
• B) 10Ω
• C) 15Ω
• D) 20Ω
Answer: A) 5Ω
Rationale: Parallel resistance formula: R_T = 1 / (1/R₁ + 1/R₂). R_T = 1 / (1/10 + 1/10)
= 5Ω. Parallel connections always result in lower total resistance than the smallest
individual resistor .
Q4. What happens to total current in a parallel circuit as additional branches are
added?
• A) It decreases
• B) It remains constant
• C) It increases
• D) It becomes zero
Answer: C) It increases
Rationale: Adding branches reduces total resistance, which increases total current
according to Ohm's Law. Each new branch provides an additional path for current
flow .
Q5. The difference in electrical potential between two points is called:
• A) Current
• B) Voltage (Potential Difference)
• C) Resistance
• D) Power
Answer: B) Voltage
Rationale: Voltage is the electrical "pressure" that pushes electrons through a circuit. It
is always measured as a difference between two points .
,Q6. 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) Coulomb
• C) Watt
• D) Henry
Answer: B) Coulomb
Rationale: 1 Ampere = 1 Coulomb per second. The Coulomb is the fundamental unit of
electric charge .
Q7. 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 (√3). 120V × √3 ≈ 208V. This is the standard 120/208V three-
phase system .
Q8. In a balanced 3-phase Wye system, what is the relationship between line
current and phase current?
• A) I_L = √3 × I_phase
• B) I_L = I_phase
• C) I_L = I_phase / √3
• D) I_L = 2 × I_phase
Answer: B) I_L = I_phase
, Rationale: In a Wye connection, line current equals phase current because there is only
one path per phase. The current flows through the line and then through the phase
winding .
Q9. In a balanced 3-phase Delta system, what is the relationship between line
current and phase current?
• A) I_L = I_phase
• B) I_L = √3 × I_phase
• C) I_L = I_phase / √3
• D) I_L = 2 × I_phase
Answer: B) I_L = √3 × I_phase
Rationale: In a Delta connection, line current is √3 times the phase current because the
line current splits between two phase windings .
Q10. What is the formula for three-phase power?
• A) P = V × I
• B) P = I² × R
• C) P = √3 × V_L × I_L × PF
• D) P = V² / R
Answer: C) P = √3 × V_L × I_L × PF
Rationale: Three-phase power is calculated using the line voltage, line current, and
power factor. The √3 factor accounts for the phase relationships in a three-phase
system .
Q11. What is the "Power Factor" of a purely resistive circuit?
• A) 0
• B) 0.5
• C) 0.707
• D) 1.0
