# Electronic Devices and Circuits Questions and Answers – The P-N Junction as a Diode

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “The P-N Junction as a Diode”.

1. How many junction/s do a diode consist?
a) 0
b) 1
c) 2
d) 3

Explanation: Diode is a one junction semiconductor device which has one cathode and anode. The junction is of p-n type.

2. If the positive terminal of the battery is connected to the anode of the diode, then it is known as
a) Forward biased
b) Reverse biased
c) Equilibrium
d) Schottky barrier

Explanation: When a positive terminal is connected to the anode, the diode is forward biased which lets the flow of the current in the circuit.

3. During reverse bias, a small current develops known as
a) Forward current
b) Reverse current
c) Reverse saturation current
d) Active current

Explanation: When the diode is reverse biased, a small current flows between the p-n junction which is of the order of the Pico ampere. This current is known as reverse saturation current.

4. If the voltage of the potential barrier is V0. A voltage V is applied to the input, at what moment will the barrier disappear?
a) V< V0
b) V= V0
c) V> V0
d) V<< V0

Explanation: When the voltage will be same that of the potential barrier, the potential barrier disappears resulting in flow of current.

5. During the reverse biased of the diode, the back resistance decrease with the increase of the temperature. Is it true or false?
a) True
b) False

Explanation: Due to the increase in the reverse saturation current due to the increase in the temperature, the back resistance decrease with the increasing temperature.
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6. What is the maximum electric field when Vbi=2V , VR=5V and width of the semiconductor is 7cm?
a) -100V/m
b) -200V/m
c) 100V/m
d) 200V/m

Explanation: Emax=-2(Vbi+VR)/W
=-2(2+5)/ (7*10-2)
=-200V/m.

7. When the diode is reverse biased with a voltage of 6V and Vbi=0.63V. Calculate the total potential.
a) 6V
b) 6.63V
c) 5.27V
d) 0.63V

Explanation: Vt=Vbi+VR
=0.63+6
=6V.

8. It is possible to measure the voltage across the potential barrier through a voltmeter?
a) True
b) False

Explanation: The contacts of the voltmeter have some resistance which will not accurately measure the voltage across the potential barrier. Thus, it is not possible to measure the voltage across the potential barrier.

9. What will be the output of the following circuit? (Assume 0.7V drop across the diode)

a) 12V
b) 12.7V
c) 11.3V
d) 0V

Explanation: V=12-0.7
=11.3V.

10. Which of the following formula represents the correct formula for width of the depletion region?
a)
b)
c)
d)

Explanation: Correct formula for width of the depletion region is:

Sanfoundry Global Education & Learning Series – Electronic Devices and Circuits.

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