EIAT Basic Electrical Principles 4 — Questions and Answers
Question 1: What does the acronym 'EMF' stand for in electrical engineering?
- Electrical Magnetic Force
- Electromotive Force (Correct answer)
- Electromagnetic Field
- Electron Motion Factor
Correct answer: Electromotive Force
EMF stands for Electromotive Force, which is the energy per unit charge supplied by a source like a battery or generator.
Question 2: A motor nameplate shows 240V, 10A. What is the motor's power rating?
- 24 W
- 2400 W (Correct answer)
- 240 W
- 24000 W
Correct answer: 2400 W
Power = V × I = 240 × 10 = 2400 W (2.4 kW).
Question 3: What is the purpose of a circuit breaker compared to a fuse?
- A circuit breaker can be reset after tripping; a fuse must be replaced (Correct answer)
- A circuit breaker is slower to react than a fuse
- A circuit breaker only works on DC circuits
- A circuit breaker provides higher resistance than a fuse
Correct answer: A circuit breaker can be reset after tripping; a fuse must be replaced
A circuit breaker is a resettable protective device, while a fuse is a one-time-use device that must be replaced after it blows.
Question 4: In a three-phase power system, what is the phase difference between each voltage waveform?
- 90 degrees
- 120 degrees (Correct answer)
- 180 degrees
- 60 degrees
Correct answer: 120 degrees
In a balanced three-phase system, the three voltage waveforms are evenly spaced 120 degrees apart.
Question 5: What happens to current in a series circuit if one component fails (opens)?
- Current increases in the remaining components
- Current continues through the remaining components
- Current flow stops completely (Correct answer)
- Current reverses direction
Correct answer: Current flow stops completely
In a series circuit, all components share the same single path, so an open in any component stops all current flow.
Question 6: What is the primary function of an inductor in an electrical circuit?
- Store energy in an electric field
- Convert AC to DC
- Store energy in a magnetic field and oppose changes in current (Correct answer)
- Amplify voltage signals
Correct answer: Store energy in a magnetic field and oppose changes in current
An inductor stores energy in a magnetic field and resists changes in current flow through it.
Question 7: Which law states that the total current entering a junction equals the total current leaving it?
- Ohm's Law
- Kirchhoff's Voltage Law
- Kirchhoff's Current Law (Correct answer)
- Faraday's Law
Correct answer: Kirchhoff's Current Law
Kirchhoff's Current Law (KCL) states that the algebraic sum of currents at any node in a circuit is zero.
EIAT Basic Electrical Principles 4
What does the acronym 'EMF' stand for in electrical engineering?