WTMA Basic Electrical Principles 5 — Questions and Answers
Question 1: What does a transformer do in an electrical system?
- Changes voltage from one level to another (Correct answer)
- Converts AC to DC
- Stores electrical energy
- Measures current flow
Correct answer: Changes voltage from one level to another
A transformer uses electromagnetic induction to step voltage up or down between two circuits while transferring power.
Question 2: Which factor does NOT affect the resistance of a wire?
- Color of the wire's insulation (Correct answer)
- Length of the wire
- Material of the wire
- Cross-sectional area of the wire
Correct answer: Color of the wire's insulation
The insulation color is a labeling convention only; resistance depends on length, material, and cross-sectional area.
Question 3: As the length of a wire doubles, its resistance:
- Doubles (Correct answer)
- Halves
- Stays the same
- Quadruples
Correct answer: Doubles
Resistance is directly proportional to length; twice the length means twice as much resistance.
Question 4: What is the function of a circuit breaker?
- To automatically disconnect the circuit when current exceeds a set limit (Correct answer)
- To boost voltage in the circuit
- To convert AC to DC power
- To balance loads across phases
Correct answer: To automatically disconnect the circuit when current exceeds a set limit
A circuit breaker automatically trips and interrupts current when it exceeds a safe threshold, and can be reset after the fault is cleared.
Question 5: In which type of circuit does current have only one path to follow?
- Series circuit (Correct answer)
- Parallel circuit
- Short circuit
- Open circuit
Correct answer: Series circuit
In a series circuit, all components are connected end-to-end forming a single loop with only one path for current.
Question 6: A 60-watt bulb operates on 120 volts. How much current does it draw?
- 0.5 amperes (Correct answer)
- 7,200 amperes
- 2 amperes
- 60 amperes
Correct answer: 0.5 amperes
Using I = P/V: I = 60 W ÷ 120 V = 0.5 amperes.
Question 7: What does the term 'open circuit' mean?
- The circuit has a break and no current flows (Correct answer)
- Current flows freely with no resistance
- The circuit has too much current
- Voltage is at its maximum
Correct answer: The circuit has a break and no current flows
An open circuit is one where the path for current is broken, so no current can flow through it.
WTMA Basic Electrical Principles 5
What does a transformer do in an electrical system?