Power electronics MCQ #13

1) The resistance of a diode is equal to 
      a) Ohmic resistance of the P- and N- semiconductors
      b) Junction resistance
      c) Reverse resistance
      d) Algebraic sum of (a) and (b) above

2) When forward biased, a diode 
      a) Blocks current            
      b) conducts current
      c) Has a high resistance 
      d) drops a large voltage.

3) At room temperature of 25 °C, the barrier potential for silicon is 0.7 V.
lts value at 125° C is 
      a) 0.5V 
      b) 0.3V 
      c) 0.9V 
      d) 0.7V

4) An electron has 
      a) positive charge 
      b) Negative Charge 
      c) Neutral 
      d) none

Answer: | 1-d | 2-b | 3-a | 4-b |


5) Zener breakdown occurs 
      a) Due to normally generated minority carriers 
      b) In lightly doped junctions
      c) Due to rupture of covalent bonds 
      d) Mostly in germanium junctions.

6) Which of the following is not a semiconductor 
      a) Gallium Arsenide 
      b) Indium 
      c) Germanium 
      d) Silicon

7) The depletion region in a PN Junction diode is due to 
      a) Reverse biasing 
      b) Forward biasing
      c) Area Created by Crystal doping 
      d) an area void of current carriers

8) Forward bias resistance of ideal diode is 
      a) 10 ohms 
      b) 1M ohms 
      c) Infinity 
      d) zero

Answer: | 5-c | 6-b | 7-d | 8-d |


9) Emission coefficient of silicon (η) is 
      a) 0    
      b) 1   
      c) 2   
      d) None

10) The static resistance of a Diode is 
      a) its opposes the D.C current flow
      b) its opposes the A.C current flow
      c) resistance of the diode when forward bias
      d) none

11) A breakdown which is caused by cumulative multiplication of carriers
through filed induced impact ionization occurs in 
      a) Zener diode 
      b) Tunnel diode 
      c) Varactor diode 
      d) avalanche diode

12) The capacitance appearing across a reverse biased semiconductor junction 
      a) increases with increase in bias voltage
      b) decreases with increase in bias voltage
      c) is independent of bias voltage
      d) none of these

Answer: | 9-c | 10-a | 11-d | 11-b |

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