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Quiz Chapter 6: Electricity and Magnetism

10 questions · Form 3 Science Bab 6: Electricity and Magnetism

10 questions · plays in fullscreen

Full Question List & Answer Key

Prefer reading to quizzing? All 10 questions are listed below with the answer and explanation under each one.

1. Where is a step-UP transformer placed within the National Grid Network?

  1. Between step-down sub-stations and residential homes
  2. Inside domestic consumer units
  3. Immediately after the power station generator
  4. Between high-voltage transmission lines and light industry
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Answer: C

Step-up transformers are located right at power stations to raise generated voltage (e.g. 11 kV or 25 kV) up to 132-500 kV before grid transmission.

2. Which wiring system is designed for large industrial manufacturing plants requiring $415 V$ operating voltage?

  1. Single-phase wiring
  2. Two-phase wiring
  3. Three-phase wiring
  4. Parallel d.c. wiring
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Answer: C

Three-phase wiring delivers $415 V$ heavy-duty electrical supply suited for high-demand industrial machinery.

3. What color code is used for the LIVE wire in modern Malaysian standard fixed electrical wiring?

  1. Blue
  2. Green and yellow stripes
  3. Brown
  4. Black
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Answer: C

Under standard electrical color coding, Brown is Live, Blue is Neutral, and Green/Yellow stripes indicate Earth.

4. Which device directly converts solar energy into electrical energy without utilizing a rotating turbine or generator?

  1. Solar collector panel
  2. Photovoltaic solar cell
  3. Solar thermal reflector
  4. Thermocouple
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Answer: B

Photovoltaic cells directly convert photon energy from sunlight into direct current (d.c.) electricity without moving mechanical parts.

5. Which component in a transformer enables the transfer of magnetic flux between the primary and secondary coils?

  1. Copper earth plate
  2. Laminated soft iron core
  3. Aluminum shield
  4. Plastic insulator case
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Answer: B

A soft iron core easily magnetizes and demagnetizes, concentrating magnetic flux lines to link the primary and secondary coils efficiently.

6. On what scientific principle does an electric generator operate to produce electricity?

  1. Thermionic emission
  2. Electromagnetic induction
  3. Electrostatic discharge
  4. Photoelectric effect
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Answer: B

Generators produce electricity by moving a conductor through a magnetic field (or rotating a magnet inside a coil) via electromagnetic induction.

7. What visual waveform appears on the screen of a Cathode Ray Oscilloscope (C.R.O.) when connected to a direct current (d.c.) voltage source with the time-base turned ON?

  1. Sinusoidal wave
  2. Square wave
  3. Straight horizontal line
  4. Vertical line
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Answer: C

Direct current flows in one direction with constant magnitude, producing a single horizontal line offset from the center on a C.R.O.

8. Which condition must be met for a transformer to step DOWN a supply voltage?

  1. Number of secondary turns ($N_s$) > Primary turns ($N_p$)
  2. Number of secondary turns ($N_s$) < Primary turns ($N_p$)
  3. Primary current ($I_p$) < Secondary current ($I_s$)
  4. Primary voltage ($V_p$) < Secondary voltage ($V_s$)
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Answer: B

A step-down transformer decreases output voltage by having fewer turns in the secondary coil than in the primary coil ($N_s < N_p$).

9. Why why electricity transmitted at extremely high voltages (e.g., 132 kV to 500 kV) through the National Grid Network?

  1. To increase current speed along cables
  2. To reduce current and minimize power lost as heat ($P = I2 R$)
  3. To eliminate the need for step-down sub-stations
  4. To prevent electrical theft along high-voltage pylons
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Answer: B

Stepping up voltage reduces transmission current ($I$). Since power loss as heat in cables depends on $I2 R$, lower current dramatically reduces energy loss.

10. What power supply voltage and frequency are standardized for domestic residential homes in Malaysia?

  1. 110 V, 60 Hz a.c.
  2. 240 V, 50 Hz a.c.
  3. 240 V, 50 Hz d.c.
  4. 415 V, 50 Hz a.c.
Show answer

Answer: B

The Malaysian standard domestic single-phase electricity supply is 240 V alternating current (a.c.) at a frequency of 50 Hz.

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