ELECTRONICS ENGINEERING – SEMICONDUCTOR DIODE MCQs

 

This section of Electronics engineering Multiple Choice Questions and Answers (MCQs) focuses on the “ Semiconductor Diode ”. These MCQs are very helpful for the preparation of  University exams, Engineering exams, and various Technical competitive exams.

ELECTRONICS ENGINEERING – SEMICONDUCTOR DIODE MCQs

1. Which of the following is the characteristic of a Forward bias diode.

A) Low resistance
B) Very high current
C) Reduced depletion width
D) All of the above

ANSWER= (D) All of the above
Explanation:- In a forward bias diode depletion width is narrow and provides low resistance to the electron flow, so the very high current flows through the diode.
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2.In a diode the reverse saturation current doubles for each…………… rise in temperature.

A) 2°C
B) 10°C
C) 20°C
D) 1°C

ANSWER= (B) 10°C
Explanation:- Reverse saturation current doubles for each 10°C rise in temperature and voltage across diode reduces by 25mV for each 10°C increase in temperature.
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3. Which one of the following is the effect of temperature on diode:

A) Cut in voltage decrease with the increase in temperature.
B) Breakdown voltage decrease with the increase in temperature.
C) Reverse saturation current decreases with the increase in temperature.
D) All of the above.

ANSWER= (A) Cut in voltage decrease with the increase in temperature.
Explanation:- The effects of the temperature on the diode are: (i)Cut in voltage decrease with the increase in temperature. (ii)Breakdown voltage increases with the increase in temperature. (iii) Reverse saturation current increases with the increase in temperature.
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4. The forward voltage at which the current through the PN junction starts to increase rapidly is known as:

A) Breakdown Voltage
B) Peak inverse voltage
C) Knee voltage
D) None of the above.

ANSWER= (C) Knee voltage
Explanation:- Knee voltage: It is the forward voltage at which the current through the PN junction starts to increase rapidly.
Breakdown Voltage: It is the reverse voltage at which the PN junction breaks down with a sudden rise in reverse current.
Peak inverse voltage: It is the maximum reverse voltage that a PN junction can withstand without damaging itself.
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5. The capacitance which exists in the forward bias P-N junction is called as:

A) Depletion capacitance
B) Diffusion capacitance
C) Transition capacitance
D) Space charge capacitance.

ANSWER= (B) Diffusion capacitance
Explanation:- The capacitance which exists in the forward bias P-N junction is called Diffusion capacitance or Storage capacitance, while the capacitance which exists in the reverse bias Pn junction is called Transition capacitance or Depletion capacitance, or Space charge capacitance.
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6. The barrier potential in a semiconductor diode opposes the flow of:

A) Electron in N region
B) Holes in the P region.
C) Minority carriers in both regions.
D) Majority carriers in both the regions.

ANSWER= (D) Majority carriers in both the regions.
Explanation:- Due to the immobile positive ion on the N side and negative ions on the P side a potential barrier is created that opposes the flow of majority carriers to cross the junction.
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7. Avalanche breakdown occurs in a heavily doped reverse bias P-N junction diode.

A) True
B) False

ANSWER= (B) False
Explanation:- Avalanche breakdown occurs in a lightly doped reverse bias P-N junction diode while Zener breakdown, whereas Zener breakdown occurs in a heavily doped reverse bias P-N junction diode.
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8. In a P-N junction diode if the reverse voltage is increased then the current due to minority charge carrier at constant temperature will :

A) increase
B) decrease
C) remains constant
D) none of the above

ANSWER= (C) remains constant
Explanation:- Current due to minority charge carrier depends on temperature and is independent of the reverse voltage applied. So if the temperature remains constant then the current will also not change.
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9. Under Reverse bias condition ideal diode act as: 

A) short circuit.
B) open circuit.
C) on switch.
D) none of these.

ANSWER= (B) open circuit.
Explanation:- Ideal diode has infinite resistance under reverse bias condition, so it acts as an open circuit or off switch.
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10. When a forward voltage is applied to a P-N junction diode, it:

A) lowers the potential barrier.
B) raises the potential barrier.
C) increases the depletion width.
D) decreases the majority carrier current.

ANSWER= (A) lowers the potential barrier
Explanation:- A diode under forward bias condition has low resistance and high majority current due to low barrier potential and reduced depletion width.
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