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Alternating current - Quiz
Contributed by: Gibson
  • 1. How does alternating current differ from direct current?
A) It stays at a fixed magnitude at all times.
B) It requires no voltage to function.
C) It flows only in one constant direction.
D) It periodically reverses direction and changes magnitude.
  • 2. What is the typical waveform of alternating current in power circuits?
A) Sawtooth wave
B) Triangular wave
C) Sine wave
D) Square wave
  • 3. Why is alternating current used for power distribution?
A) It does not require any wires for transmission.
B) Its voltage can be increased or decreased with a transformer.
C) It travels faster than direct current.
D) It is safer to touch than direct current.
  • 4. According to the formula Pw = I2R, how is power loss affected if current is halved?
A) It is reduced by a factor of four.
B) It remains the same.
C) It increases by a factor of four.
D) It is reduced by half.
  • 5. What happens to energy loss when transmission voltage is increased?
A) Energy loss remains constant.
B) Energy loss due to heat is increased.
C) Energy loss becomes zero instantly.
D) Energy loss due to heat is reduced.
  • 6. In a three-phase generator, what is the physical offset between the three coils?
A) 120 degrees
B) 60 degrees
C) 90 degrees
D) 180 degrees
  • 7. What is the benefit of a 12-pole generator compared to a 2-pole generator?
A) It can operate at lower rotational speeds.
B) It produces a higher frequency.
C) It generates less voltage.
D) It uses more electricity.
  • 8. What is the purpose of the bond or earth wire?
A) To convert AC to DC power.
B) To increase the power output of the device.
C) To balance the three-phase load.
D) To provide a low impedance path to ground for safety.
  • 9. What is the primary reason high-voltage DC was not used in early power systems?
A) It was too dangerous to transport.
B) Lack of an economically viable way to step down voltage.
C) It only worked for very short distances.
D) It was incompatible with copper wire.
  • 10. What can cause neutral conductor current to exceed phase current levels?
A) Using standard incandescent bulbs.
B) Non-linear loads and harmonics.
C) Perfectly balanced three-phase loads.
D) Using only resistive loads.
  • 11. What is the common voltage range for domestic use mentioned in the text?
A) 50 V – 100 V
B) 100 V – 240 V
C) 500 V – 1000 V
D) 10 V – 50 V
  • 12. What does a guitar amplifier use that differs from standard power AC?
A) Only direct current.
B) Lower frequencies than power distribution.
C) Higher constant voltages.
D) Different waveforms like square or triangular waves.
  • 13. What happens if a three-phase load is perfectly balanced?
A) No current flows through the neutral point.
B) The neutral current doubles.
C) The voltage becomes unstable.
D) The generator stops working.
  • 14. What is the advantage of using a center-tapped transformer on UK construction sites?
A) It eliminates the need for grounding.
B) It allows for higher current transmission.
C) It increases the frequency of the tools.
D) It reduces the risk of electric shock.
  • 15. What is a full period of a sine wave called?
A) A bond
B) A phase
C) A harmonic
D) A cycle
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