LADWP Utility Electrical Craft Helper -
Exam No. 3851 Exam Practice Questions
and Correct Answers (Verified Answers)
Plus Rationale 2026 Q&A| Instant
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1. Electrical Safety
What is the most important reason an electrical circuit should be de-energized
before maintenance when the work procedure permits it?
A. To increase conductor resistance
B. To reduce the risk of electrical shock and arc-related injury
C. To improve the circuit's power factor
D. To increase available fault current
Rationale: De-energizing equipment removes the normal source of electrical
energy and substantially reduces the shock and arc hazards associated with
energized work. Required isolation and verification procedures must still be
followed.
2. Voltage
What does electrical voltage represent?
A. The rate of electron flow
B. Opposition to current
C. Electrical power consumption
D. Electrical potential difference between two points
,Rationale: Voltage is the electrical potential difference that provides the driving
force for current through a circuit. It is measured in volts.
3. Current
What is the unit used to measure electric current?
A. Ohm
B. Ampere
C. Watt
D. Volt
Rationale: Electric current is measured in amperes, commonly abbreviated as
amps or A. Current represents the rate of movement of electric charge.
4. Resistance
Which unit is used to measure electrical resistance?
A. Volt
B. Ampere
C. Ohm
D. Watt
Rationale: Electrical resistance is measured in ohms (Ω). Resistance describes how
strongly a material or component opposes current flow.
5. Ohm's Law
A circuit has a resistance of 10 ohms and a voltage of 120 volts. What current
flows through the resistance?
A. 0.083 A
B. 10 A
C. 1200 A
D. 12 A
Rationale: Ohm's law states that I = V/R. Therefore, 120 V ÷ 10 Ω = 12 A.
6. Electrical Power
Which formula correctly represents electrical power in a basic DC circuit?
,A. P = R/I
B. P = V/R
C. P = V × I
D. P = I/R
Rationale: Electrical power is calculated by multiplying voltage by current. Thus, P
= VI, with power measured in watts.
7. Conductors
Which material is commonly used as an electrical conductor because of its high
conductivity?
A. Rubber
B. Glass
C. PVC
D. Copper
Rationale: Copper has high electrical conductivity and is widely used for electrical
conductors. Materials such as rubber, glass, and PVC are commonly used as
insulators.
8. Insulators
What is the primary function of insulation around an electrical conductor?
A. Increase current flow
B. Restrict unintended current flow and provide electrical separation
C. Increase conductor temperature
D. Increase circuit frequency
Rationale: Electrical insulation prevents current from flowing between the
conductor and unintended conductive surfaces. Proper insulation helps protect
personnel and equipment.
9. Series Circuit
In a simple series circuit, how does current behave through the individual
components?
A. It is different through every component.
B. It is zero at the first component.
, C. The same current flows through each component.
D. It doubles after each component.
Rationale: A series circuit provides a single path for current. Therefore, the same
current passes sequentially through each series component.
10. Parallel Circuit
What is a defining characteristic of a parallel circuit?
A. It has only one possible current path.
B. It provides multiple current paths between common connection points.
C. Current must be identical in every branch regardless of resistance.
D. The total resistance is always greater than every branch resistance.
Rationale: Parallel branches provide separate paths for current. The current
divides among the branches according to their impedances or resistances.
11. Series Resistance
Two 5-ohm resistors are connected in series. What is their total resistance?
A. 0.5 Ω
B. 2.5 Ω
C. 5 Ω
D. 10 Ω
Rationale: Series resistances add directly: 5 Ω + 5 Ω = 10 Ω.
12. Parallel Resistance
Two identical 10-ohm resistors are connected in parallel. What is their equivalent
resistance?
A. 20 Ω
B. 10 Ω
C. 5 Ω
D. 2 Ω
Rationale: Two equal resistors connected in parallel have an equivalent resistance
equal to one-half the resistance of either resistor. Thus, 10 Ω ÷ 2 = 5 Ω.
13. Open Circuit
Exam No. 3851 Exam Practice Questions
and Correct Answers (Verified Answers)
Plus Rationale 2026 Q&A| Instant
Download Pdf
1. Electrical Safety
What is the most important reason an electrical circuit should be de-energized
before maintenance when the work procedure permits it?
A. To increase conductor resistance
B. To reduce the risk of electrical shock and arc-related injury
C. To improve the circuit's power factor
D. To increase available fault current
Rationale: De-energizing equipment removes the normal source of electrical
energy and substantially reduces the shock and arc hazards associated with
energized work. Required isolation and verification procedures must still be
followed.
2. Voltage
What does electrical voltage represent?
A. The rate of electron flow
B. Opposition to current
C. Electrical power consumption
D. Electrical potential difference between two points
,Rationale: Voltage is the electrical potential difference that provides the driving
force for current through a circuit. It is measured in volts.
3. Current
What is the unit used to measure electric current?
A. Ohm
B. Ampere
C. Watt
D. Volt
Rationale: Electric current is measured in amperes, commonly abbreviated as
amps or A. Current represents the rate of movement of electric charge.
4. Resistance
Which unit is used to measure electrical resistance?
A. Volt
B. Ampere
C. Ohm
D. Watt
Rationale: Electrical resistance is measured in ohms (Ω). Resistance describes how
strongly a material or component opposes current flow.
5. Ohm's Law
A circuit has a resistance of 10 ohms and a voltage of 120 volts. What current
flows through the resistance?
A. 0.083 A
B. 10 A
C. 1200 A
D. 12 A
Rationale: Ohm's law states that I = V/R. Therefore, 120 V ÷ 10 Ω = 12 A.
6. Electrical Power
Which formula correctly represents electrical power in a basic DC circuit?
,A. P = R/I
B. P = V/R
C. P = V × I
D. P = I/R
Rationale: Electrical power is calculated by multiplying voltage by current. Thus, P
= VI, with power measured in watts.
7. Conductors
Which material is commonly used as an electrical conductor because of its high
conductivity?
A. Rubber
B. Glass
C. PVC
D. Copper
Rationale: Copper has high electrical conductivity and is widely used for electrical
conductors. Materials such as rubber, glass, and PVC are commonly used as
insulators.
8. Insulators
What is the primary function of insulation around an electrical conductor?
A. Increase current flow
B. Restrict unintended current flow and provide electrical separation
C. Increase conductor temperature
D. Increase circuit frequency
Rationale: Electrical insulation prevents current from flowing between the
conductor and unintended conductive surfaces. Proper insulation helps protect
personnel and equipment.
9. Series Circuit
In a simple series circuit, how does current behave through the individual
components?
A. It is different through every component.
B. It is zero at the first component.
, C. The same current flows through each component.
D. It doubles after each component.
Rationale: A series circuit provides a single path for current. Therefore, the same
current passes sequentially through each series component.
10. Parallel Circuit
What is a defining characteristic of a parallel circuit?
A. It has only one possible current path.
B. It provides multiple current paths between common connection points.
C. Current must be identical in every branch regardless of resistance.
D. The total resistance is always greater than every branch resistance.
Rationale: Parallel branches provide separate paths for current. The current
divides among the branches according to their impedances or resistances.
11. Series Resistance
Two 5-ohm resistors are connected in series. What is their total resistance?
A. 0.5 Ω
B. 2.5 Ω
C. 5 Ω
D. 10 Ω
Rationale: Series resistances add directly: 5 Ω + 5 Ω = 10 Ω.
12. Parallel Resistance
Two identical 10-ohm resistors are connected in parallel. What is their equivalent
resistance?
A. 20 Ω
B. 10 Ω
C. 5 Ω
D. 2 Ω
Rationale: Two equal resistors connected in parallel have an equivalent resistance
equal to one-half the resistance of either resistor. Thus, 10 Ω ÷ 2 = 5 Ω.
13. Open Circuit
