# PN Diode Switching Times MCQ’s

This set of Electronic Devices & Circuits Multiple Choice Questions & Answers (MCQs) focuses on “PN Diode Switching Times”.

1. Reverse recovery time for a diode is?
a) Time taken to eliminate excess minority charge carriers
b) Sum of storage time (TS) and transition time (TT)
c) Time taken to eliminate excess majority charge carriers
d) Time elapsed to return to non conduction state

2. Switching speed of P+ junction depends on.
a) Mobility of minority carriers in P junction
b) Life time of minority carriers in P junction
c) Mobility of majority carriers in N junction
d) Life time of minority carriers in N junction

3. Diode acts as a short circuit when switched from forward to reverse bias for some time due to______
a) Accumulation of minority charge carriers when it’s in forward bias
b) Accumulation of majority charge carriers when it’s in forward bias
c) Accumulation of minority charge carriers when it’s in reverse bias
d) Accumulation of majority charge carrier when it’s in reverse bias

4. Time taken for a diode to reach 90% of its final value when switched from steady state is______
a) 2.3*time constant
b) 2.2*time constant
c) 1.5*time constant
d) equals the time constant

5. In a circuit below, the switch is at position 1 at t<0 and at position 2 when t=0. Assume diode has zero voltage drop and storage time. For 0<t<ts, the VR at 1k ohm resistor is given by_____

a) 5V
b) -5V
c) 0v
d) 10V

6. A PN junction diode with 100Ω resistor is forward biased such that 100A current flows. If voltage across this combination is instantaneously reversed to 10V at t=0, the reverse current that flows through diode at t=0 is?

a) 10mA
b) 100mA
c) -100mA
d) -10mA

7. Which of the following are true?
1) In reverse bias, the diode undergoes stages of storage and transition times
2) Minority charge carriers accumulation makes the diode as a short circuit
3) Storage time is the sum of recovery and transition times
a) 1 only
b) 2 and 3
c) 3 only
d) 1 and 2 only

8. The switch is at position shown in the figure initially and steady state is from t=0 to t=to. The switch suddenly is thrown to the other position. The current flowing through the 10K resistor from t=0 is?

a) 1mA
b) 2mA
c) -2mA
d) -1mA

9. The delay in switching between the ON and OFF states is due to _________
a) The time required to change amount of excess minority carriers stored in quasi-neutral regions
b) The time required to change amount of excess majority carriers stored in quasi-neutral regions
c) The conduction between storage time and recovery time
d) The exponential increase in carriers in N region

10. The delay time can be reduced by?
a) decreasing lifetime and increasing ratio of reverse to forward current
b) increasing lifetime and decreasing ratio of reverse to forward current
c) increasing lifetime and increasing ratio of reverse to forward current
d) decreasing lifetime and decreasing ratio of reverse to forward current