# Power Electronics Questions and Answers – Types of Diodes-2

This set of Power Electronics Multiple Choice Questions & Answers (MCQs) focuses on “Types of Power Diodes-2”.

1. Ideally the voltage drop across a conducting diode must be
a) ∞
b) 0
c) higher than the forward biased voltage
d) equal to the forward biased voltage

Explanation: Ideal conduction = No losses.

2. When reverse breakdown occurs in a diode
a) voltage increases & current is constant
b) voltage increases & current also increases
c) both are constant
d) voltage is constant & current increases

Explanation: Recall the I-V curve of a diode in the 3rd quadrant.

3. Schottky diodes are also called as
a) metal diode
b) hot carrier diode
c) signaling diode
d) easy turn on diode

Explanation: Due to the metal used to carry the current, it is also called as a hot carrier diode.

4. In a Schottky diode, the aluminum metal acts as a __________
a) anode
b) cathode
c) gate
d) common terminal

Explanation: The Al (Metal) always acts as the anode.

5. If the doping levels of the semiconductor is increased, then the width of the depletion layer
a) increases
b) decreases
c) is unchanged
d) keeps oscillating

Explanation: Higher the doping, more the number of charge carrier available to neutralize the opposite charges on the junction.
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6. As compared to a p-n junction device of equal rating, the Schottky diode has
a) lower reverse voltage rating
b) lower reverse leakage current
c) higher Switching time
d) higher cut-in voltage

Explanation: Low reverse voltage rating is the only drawback against a p-n junction diode.

7. In a Schottky diode, the silicon layer acts as a _____________
a) anode
b) cathode
c) gate
d) common terminal

Explanation: The metal acts as the anode and the semiconductor as a cathode.

8. In a certain power electronics application, it is required that the voltage at the load terminals is to be kept within a certain range of voltages only. Among the device listed below, which would be the most ideal choice for this application?
a) P-n junction diode
b) Schottky diode
c) Zener diode
d) Fast recover diode

Explanation: Zener diode is used as a voltage regulating device.

9. Shown below is the diagram of an ideal super diode. When the input voltage Vin is positive, then the output voltage Vout = ?

a) Vout/Vin
b) Vin
c) 0
d) Vin * Rl

Explanation: Input is positive, hence it is amplified by the operational amplifier which switches the diode on. Current flows through the load & because of the feedback, the output voltage is equal to the input voltage.

10. Zener diodes allow a current to flow in the reverse direction, when the
a) voltage reaches above a certain value
b) temperature reaches above a certain value
c) current always flows in the reverse direction only
d) current cannot flow in the reverse direction

Explanation: Zener diode has voltage regulating property. When voltage reaches above a certain value (Zener voltage), current starts to flow in the reverse direction.

Sanfoundry Global Education & Learning Series – Power Electronics.

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