PN Junction Diode Multiple Choice Questions Answers
Que.1 A p-n junction diode’s dynamic conductance is directly proportional to
- (a)The applied voltage
- (b)The temperature
- (c) It’s current
- (d)The thermal voltage
Que.2 The AC resistance of a forward-biased p-n junction diode operating at a bias voltage ‘V’ and carrying current ‘I’ is
- (a) zero
- (b) a constant value independent of V and I
- (c) V/I
- (d) ΔV/ΔI
Que.3 The depletion layer across a p+-n junction lies
- (a) mostly in the p+ – region
- (b) mostly in the n – region
- (c) equally in both the p+and n-regions
- (d) entirely in the p+ – regions
Que.4 The change in barrier potential of a silicon p-n junction with temperature is
- (a) 0.0025 Volts per degree C
- (b) 0.0250 Volts per degree C
- (c) 0.0030 Volts per degree C
- (d) 0.0014 Volts per degree C
Que.5 The diffusion capacitance of a p-n junction diode
- (a) Increases exponentially with forwarding bias voltage
- (b) Decreases exponentially with forwarding bias voltage
- (c) Decreases linearly with forwarding bias voltage
- (d) Increases linearly with forwarding bias voltage
Que.6 The reverse current of a silicon diode is
- (a) Highly bias voltage-sensitive
- (b) Highly temperature sensitive
- (c) Both bias voltage and temperature-sensitive
- (d) Independent of bias voltage and temperature
Que.7 A combination of two diodes connected in parallel when compared to a single diode can withstand
- (a) Twice the value of peak inverse voltage
- (b) Twice the value of maximum forward current
- (c) A larger leakage current
- (d) Twice the value of cut-in voltage
Que.8 In switching diode fabrication, the dopant is introduced into silicon which introduces additional trap levels in the material thereby reducing the mean lifetime of carriers. This dopant is
- (a) Aluminium
- (b) Platinum
- (c) Gold
- (d) Copper
Que.9 When a junction diode is used in switching applications, the forward recovery time is
- (a) of the order of the reverse recovery time
- (b) negligible in comparison to the reverse recovery time
- (c) greater than the reverse recovery time
- (d) equal to the mean carrier lifetime for the excess minority carriers.
Que.10 The depletion region in a semiconductor p-n junction diode has
- (a) Electrons and holes
- (b) Positive and negative ions on either side
- (c) Neither electrons nor ions
- (d) No holes
Que.11 The junction capacitance of a p-n junction depends on
- (a) Doping concentration only
- (b) Applied voltage only
- (c) Both doping concentration and applied voltage
- (d) Barrier potential only
Que.12 When a positive d.c. voltage is applied to the n-side relative to the p-side, a diode is said to be given a
- (a) forward bias
- (b) reverse bias
- (c) zero bias
- (d) neutral bias
Que.13 The depletion layer in a p-n junction is made of which of the following?
- (a) ionized donors on the p-side and ionized acceptors in n-side
- (b) ionized acceptors in p-side donors in n-side and ionized
- (c) Accumulated holes in the p-side and accumulated electrons in n-side
- (d) Accumulated electrons on the p-side and accumulated holes in n-side
Que.14 In a step-graded p-n junction diode, what is the ratio of depletion-region penetration depths into p and n regions (if the ratio of acceptor to donor impurity atoms’ densities is 1:2)?
- (a) 2:1
- (b) 4:1
- (c) 1:2
- (d) 1:4
Que.15 What is the typical value for the ratio of current in a p-n junction diode in the forward bias and that in the reverse bias?
- (a) 1
- (c) 100
- (b) 10
- (d) 1000
Que.16 Which junction has the least junction capacitance?
- (a) Alloy
- (b) Grown
- (c) Diffused
- (d) Point Contact
Que.17 A heavily doped semiconductor has
- (a) a resistivity that decreases exponentially with temperature
- (b) a resistivity that rises almost linearly with temperature
- (c) a negative temperature coefficient of resistance
- (d) a positive temperature coefficient of resistance
Que.18 With the increase of reverse bias in a p-n diode, the reverse current
- (a) decreases
- (b) increases
- (c) remains constant
- (d) may increase or decrease depending upon doping
Que.19 In a semiconductor diode, cut-in voltage is the voltage
- (a) up to which the current is zero
- (b) up to which the current is very small
- (c) at which the current is 10% of the maximum rated current
- (d) at which depletion layer is formed
