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Quiz Chapter 5: Electronics

10 questions · Form 5 Physics Bab 5: Electronics

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. Which operational feature characterizes a bridge rectifier during full-wave rectification?

  1. Current passes through 2 diodes during each half-cycle
  2. Current passes through all 4 diodes simultaneously
  3. Current flows through the load resistor in opposite directions each cycle
  4. Half of the input a.c. wave energy is discarded
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Answer: A

In a bridge rectifier, two specific diodes conduct during positive half-cycle and the other two conduct during negative half-cycle.

2. An electron moving at 2.0 × 10⁷ m s⁻¹ enters an electric field in a CRT. Calculate its kinetic energy. (m = 9.1 × 10⁻³¹ kg)

  1. 1.82 × 10⁻16 J
  2. 3.64 × 10⁻16 J
  3. 1.82 × 10⁻23 J
  4. 9.10 × 10⁻17 J
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Answer: A

Ek = 0.5 × m × v² = 0.5 × (9.1 × 10⁻³¹ kg) × (2.0 × 10⁷ m s⁻¹)² = 1.82 × 10⁻¹⁶ J.

3. Identify the correct symbol representation for an npn transistor:

  1. Arrow on Emitter pointing INWARDS towards Base
  2. Arrow on Emitter pointing OUTWARDS away from Base
  3. Arrow on Collector pointing OUTWARDS
  4. Arrow on Base pointing directly to Collector
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Answer: B

In an npn transistor, the emitter arrow points outwards (Never Points iN = npn).

4. Electrons in a Cathode Ray Tube (CRT) are accelerated towards the anode by a potential difference of 2.5 kV. What is the kinetic energy acquired by each electron? (e = 1.6 × 10⁻¹⁹ C)

  1. 4.0 × 10⁻¹⁶ J
  2. 1.6 × 10⁻²² J
  3. 6.4 × 10⁻¹⁶ J
  4. 4.0 × 10⁻¹⁹ J
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Answer: A

Ek = e × V = 1.6 × 10⁻¹⁹ C × 2500 V = 4.0 × 10⁻¹⁶ J.

5. What is the effect of turning ON the Time-Base feature of a Cathode Ray Oscilloscope (CRO)?

  1. It sweeps the electron spot horizontally across the screen at a steady speed
  2. It deflects the spot vertically up and down
  3. It turns off the filament heater
  4. It converts a.c. input signals directly to d.c.
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Answer: A

The time-base applies a sawtooth voltage to horizontal X-deflection plates, sweeping the beam horizontally.

6. Which formula correctly relates the Emitter current (I_E), Base current (I_B), and Collector current (I_C) of a functioning transistor?

  1. I_B = I_E + I_C
  2. I_E = I_B + I_C
  3. I_C = I_E + I_B
  4. I_E = I_C - I_B
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Answer: B

Total current entering/leaving the transistor requires I_E = I_B + I_C.

7. What component is connected across the load resistor in a rectifier circuit to smooth out voltage ripples?

  1. Capacitor
  2. Inductor
  3. Zener diode
  4. Thermistor
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Answer: A

A capacitor acts as a smooth-filter by charging at peak voltage and discharging when rectified output voltage drops.

8. Which set of properties correctly describes cathode rays inside a vacuum tube?

  1. Electromagnetic waves, positively charged, deflected by electric field
  2. Stream of fast electrons, negatively charged, deflected towards positive plate
  3. Stream of protons, positively charged, undeflected by magnetic field
  4. Stream of neutrons, neutral charge, cause fluorescence
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Answer: B

Cathode rays consist of high-speed electrons (negative charge) that deflect toward positive electric plates.

9. What happens to the depletion layer of a p-n junction diode when connected in FORWARD BIAS?

  1. It widens and increases resistance
  2. It narrows and resistance becomes very low
  3. It disappears permanently
  4. It remains unchanged
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Answer: B

Forward bias repels charge carriers across the junction, narrowing the depletion layer and allowing current to flow.

10. What impurity element is added to pure silicon to produce an n-type semiconductor?

  1. Boron
  2. Phosphorus
  3. Indium
  4. Gallium
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Answer: B

Pentavalent impurities such as Phosphorus or Arsenic provide extra free electrons, creating an n-type semiconductor.

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