Transit Railcar Maintenance Technician – Electrical Systems Exam |
Questions and Answers with Rationales | 2026/2027 Update
Questions 1–25: Electrical Fundamentals
1. Electrical voltage is best described as:
A. The flow of electrons
B. Electrical potential difference
C. Opposition to current
D. Mechanical resistance
Answer: B
Rationale: Voltage is the electrical potential difference that drives
current through a circuit.
2. Electrical current is measured in:
A. Ohms
B. Volts
C. Amperes
D. Watts
Answer: C
Rationale: Electrical current is measured in amperes, commonly called
amps.
3. Electrical resistance is measured in:
A. Volts
B. Amperes
C. Watts
D. Ohms
Answer: D
Rationale: Resistance is measured in ohms.
,4. According to Ohm's law, current equals:
A. Voltage × resistance
B. Voltage ÷ resistance
C. Resistance ÷ voltage
D. Voltage + resistance
Answer: B
Rationale: Ohm's law states I = V ÷ R.
5. A 24-volt circuit has a resistance of 6 ohms. What current flows?
A. 2 A
B. 3 A
C. 4 A
D. 6 A
Answer: C
Rationale: I = 24 ÷ 6 = 4 amps.
6. A circuit has 12 volts and carries 3 amps. Its resistance is:
A. 4 ohms
B. 9 ohms
C. 15 ohms
D. 36 ohms
Answer: A
Rationale: R = V ÷ I = 12 ÷ 3 = 4 ohms.
7. Electrical power is calculated using:
A. P = V × I
B. P = V ÷ I
C. P = R ÷ I
D. P = V + I
,Answer: A
Rationale: Electrical power in watts equals voltage multiplied by
current.
8. A 48-volt circuit draws 5 amps. What is the power?
A. 53 W
B. 120 W
C. 240 W
D. 480 W
Answer: C
Rationale: P = 48 × 5 = 240 watts.
9. Which material is generally a good electrical conductor?
A. Rubber
B. Copper
C. Plastic
D. Glass
Answer: B
Rationale: Copper has low electrical resistance and is commonly used
in electrical wiring.
10. Which material is generally used as an electrical insulator?
A. Copper
B. Aluminum
C. Rubber
D. Silver
Answer: C
Rationale: Rubber resists electrical current and is commonly used for
insulation.
11. An open circuit generally:
, A. Allows excessive current flow
B. Prevents normal current flow
C. Reduces voltage to zero everywhere
D. Creates a direct short
Answer: B
Rationale: An open circuit interrupts the path required for current flow.
12. A short circuit is generally:
A. An unintended low-resistance path
B. A properly functioning load
C. An open connection
D. A normal fuse condition
Answer: A
Rationale: A short circuit can allow excessive current to flow through
an unintended path.
13. Conventional current flow is considered to move from:
A. Negative to positive
B. Positive to negative
C. Ground to resistance
D. Load to source only
Answer: B
Rationale: Conventional current is described as flowing from positive to
negative.
14. Resistance generally increases when a conductor becomes:
A. Shorter
B. Larger in diameter
C. Longer
D. More conductive
Questions and Answers with Rationales | 2026/2027 Update
Questions 1–25: Electrical Fundamentals
1. Electrical voltage is best described as:
A. The flow of electrons
B. Electrical potential difference
C. Opposition to current
D. Mechanical resistance
Answer: B
Rationale: Voltage is the electrical potential difference that drives
current through a circuit.
2. Electrical current is measured in:
A. Ohms
B. Volts
C. Amperes
D. Watts
Answer: C
Rationale: Electrical current is measured in amperes, commonly called
amps.
3. Electrical resistance is measured in:
A. Volts
B. Amperes
C. Watts
D. Ohms
Answer: D
Rationale: Resistance is measured in ohms.
,4. According to Ohm's law, current equals:
A. Voltage × resistance
B. Voltage ÷ resistance
C. Resistance ÷ voltage
D. Voltage + resistance
Answer: B
Rationale: Ohm's law states I = V ÷ R.
5. A 24-volt circuit has a resistance of 6 ohms. What current flows?
A. 2 A
B. 3 A
C. 4 A
D. 6 A
Answer: C
Rationale: I = 24 ÷ 6 = 4 amps.
6. A circuit has 12 volts and carries 3 amps. Its resistance is:
A. 4 ohms
B. 9 ohms
C. 15 ohms
D. 36 ohms
Answer: A
Rationale: R = V ÷ I = 12 ÷ 3 = 4 ohms.
7. Electrical power is calculated using:
A. P = V × I
B. P = V ÷ I
C. P = R ÷ I
D. P = V + I
,Answer: A
Rationale: Electrical power in watts equals voltage multiplied by
current.
8. A 48-volt circuit draws 5 amps. What is the power?
A. 53 W
B. 120 W
C. 240 W
D. 480 W
Answer: C
Rationale: P = 48 × 5 = 240 watts.
9. Which material is generally a good electrical conductor?
A. Rubber
B. Copper
C. Plastic
D. Glass
Answer: B
Rationale: Copper has low electrical resistance and is commonly used
in electrical wiring.
10. Which material is generally used as an electrical insulator?
A. Copper
B. Aluminum
C. Rubber
D. Silver
Answer: C
Rationale: Rubber resists electrical current and is commonly used for
insulation.
11. An open circuit generally:
, A. Allows excessive current flow
B. Prevents normal current flow
C. Reduces voltage to zero everywhere
D. Creates a direct short
Answer: B
Rationale: An open circuit interrupts the path required for current flow.
12. A short circuit is generally:
A. An unintended low-resistance path
B. A properly functioning load
C. An open connection
D. A normal fuse condition
Answer: A
Rationale: A short circuit can allow excessive current to flow through
an unintended path.
13. Conventional current flow is considered to move from:
A. Negative to positive
B. Positive to negative
C. Ground to resistance
D. Load to source only
Answer: B
Rationale: Conventional current is described as flowing from positive to
negative.
14. Resistance generally increases when a conductor becomes:
A. Shorter
B. Larger in diameter
C. Longer
D. More conductive
