JEE Questions for Physics Semiconductor Devices Quiz 18 - MCQExams.com

Avalanche breakdown is due to
  • Collision of minority charge carrier
  • Increase in depletion layer thickness
  • Decrease in depletion layer thickness
  • None of the above
In the given figure, which of the diodes are forward biased
Physics-Semiconductor Devices-88217.png
  • I, II, III
  • II, IV, V
  • I, III, IV
  • II, III, IV
Function of rectifier is
  • To convert ac into dc
  • To convert dc into ac
  • Both (a) and (b)
  • None of these
If the two ends P and N of a P – N diode junction are joined by a wire
  • There will not be a steady current in the circuit
  • There will be a steady current from N side to P side
  • There will be a steady current from P side to N side
  • There may not be a current depending upon the resistance of the connecting wire
In a PN–junction
  • P and N both are at same potential
  • High potential at N side and low potential at N side
  • High potential at P side and low potential at P side
  • Low potential at N side and zero potential at P side
For the given circuit of PN junction diode, which of the following statement is correct?
Physics-Semiconductor Devices-88219.png
  • In forward biasing the voltage across R is V
  • In forward biasing the voltage across R is 2V
  • In reverse biasing the voltage across R is V
  • In reverse biasing the voltage across R is 2V
On adjusting the p – N junction diode in forward biased
  • Depletion layer increases
  • Resistance increases
  • Both decreases
  • None of the above
Barrier potential of a P – N junction diode does not depend on
  • Temperature
  • Forward bias
  • Doping density
  • Diode design
Of the diodes shown in the following diagrams, which one is reverse biased

  • Physics-Semiconductor Devices-88220.png
  • 2)
    Physics-Semiconductor Devices-88221.png

  • Physics-Semiconductor Devices-88222.png

  • Physics-Semiconductor Devices-88223.png
In a PN junction photo cell, the value of photo-electromotive force produced by monochromaticlight is proportional to
  • The voltage applied at the PN junction
  • The barrier voltage at the PN junction
  • The intensity of the light falling on the cell
  • The frequency of the light falling on the cell
Which is the correct diagram of a half-wave rectifier?

  • Physics-Semiconductor Devices-88224.png
  • 2)
    Physics-Semiconductor Devices-88225.png

  • Physics-Semiconductor Devices-88226.png

  • Physics-Semiconductor Devices-88227.png
The maximum efficiency of full wave rectifier is
  • 100%
  • 25.20%
  • 40.2%
  • 81.2%
Serious draw back of the semiconductor device is
  • They cannot be used with high voltage
  • They pollute the environment
  • They are costly
  • They do not last for long time
Select the correct statement
  • In a full wave rectifier, two diodes work alternately
  • In a full wave rectifier, two diodes work simultaneously
  • The efficiency of full wave and half wave rectifiers is same
  • The full wave rectifier is bi-directional
In order to forward bias a PN junction, the negativeterminal of battery is connected to
  • P–side
  • Either P–side or N–side
  • N–side
  • None of these
The diode shown in the circuit is a silicon diode. The potential difference between the points A and B will be
Physics-Semiconductor Devices-88229.png
  • 6 V
  • 0.6 V
  • 0.7 V
  • 0 V
Zener breakdown takes place if
  • Doped impurity is low
  • Doped impurity is high
  • Less impurity in N–part
  • Less impurity in P-type
Consider the following statements A and B and identify the correct choice of the given answers (A) A zener diode is always connected in reverse bias (B) The potential barrier of a PN junction lies between 0.1 to 0.3 V approximately
  • A and B are correct
  • A and B are wrong
  • A is correct but B is wrong
  • A is wrong but B is correct
The correct symbol for zener diode is

  • Physics-Semiconductor Devices-88230.png
  • 2)
    Physics-Semiconductor Devices-88231.png

  • Physics-Semiconductor Devices-88232.png

  • Physics-Semiconductor Devices-88233.png
No bias is applied to a P — N junction, then the current
  • Is zero because the number of charge carriers flowing on both sides is same
  • Is zero because the charge carriers do not move
  • Is non-zero
  • None of the above
Zener diode is used as
  • Half wave rectifier
  • Full wave rectifier
  • Ac voltage stabilizer
  • Dc voltage stabilizer
The width of forbidden gap in silicon crystal is 1.1 eV. When the crystal is converted into a N–type semiconductor the distance of Fermi level from conduction band is
  • Greater than 0.55 eV
  • Equal to 0.55 eV
  • Lesser than 0.55 eV
  • Equal to 1.1 eV
Which is the wrong statement in following sentences? A device in which P and N–type semiconductors are used is more useful than a vacuum type because
  • Power is not necessary to heat the filament
  • It is more stable
  • Very less heat is produced in it
  • Its efficiency is high due to a high voltage across the junction
A p–n photodiode is made of a material with a band gap of 2.0 eV. The minimum frequency of the radiation that can be absorbed by the material is nearly
  • 1 × 1014 Hz
  • 20 × 1014 Hz
  • 10 × 1014 Hz
  • 5 × 1014 Hz
The current through an ideal PN–junction shown in the following circuit diagram will be
Physics-Semiconductor Devices-88239.png
  • Zero
  • 1 mA
  • 10 mA
  • 30 mA
If a full wave rectifier circuit is operating from 50 Hz mains, the fundamental frequency in the ripple will be
  • 50 Hz
  • 70.7 Hz
  • 100 Hz
  • 25 Hz
If in a p – n junction diode, a square input signal of 10 V is applied as shown
Physics-Semiconductor Devices-88240.png

  • Physics-Semiconductor Devices-88241.png
  • 2)
    Physics-Semiconductor Devices-88242.png

  • Physics-Semiconductor Devices-88243.png

  • Physics-Semiconductor Devices-88244.png
Currents flowing in each of the circuits A and Brespectively
Physics-Semiconductor Devices-88250.png
  • 1 A, 2 A
  • 2 A, 1 A
  • 4 A, 2 A
  • 2 A, 4 A
In the following circuit, the current flowing through1 kΩ resistor is
Physics-Semiconductor Devices-88252.png
  • 0 mA
  • 5 mA
  • 10 mA
  • 15 mA
Assuming the diodes to be of silicon with forward resistance zero, the current Iin the following circuit is
Physics-Semiconductor Devices-88254.png
  • 0
  • 9.65 mA
  • 10 mA
  • 10.36 mA
The value of D.C. voltage in Half wave rectifier in converting A.C. voltage V = 100 sin(314 t) into D.C. is
  • 100 volt
  • 50 volt
  • 30.3 volt
  • 0
If the voltage between the terminals A and B is 17 V and Zener breakdown voltage is 9 V, then the potentialacross R is
Physics-Semiconductor Devices-88256.png
  • 6 V
  • 8 V
  • 9 V
  • 17 V
GaAs (with a band gap = 1.5 eV) as an LED can emit
  • Blue light
  • Green light
  • Ultraviolet rays
  • X-rays
  • Infrared rays
Application of a forward bias to a p — n junction
  • increases the number of donors on the n–side
  • increases the electric field in the depletion zone
  • increases the potential difference across the depletion zone
  • widens the depletion zone
In the given circuit for ideal diode, the current through the battery is
Physics-Semiconductor Devices-88260.png
  • 0.5 A
  • 1.5 A
  • 1.0 A
  • 2 A
A zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in figure. The current through the diode is
Physics-Semiconductor Devices-88262.png
  • 20 mA
  • 5 mA
  • 10 mA
  • 15 mA
Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is
Physics-Semiconductor Devices-88264.png
  • 0.75 A
  • Zero
  • 0.25 A
  • 0.5 A
In an NPN transistor the collector current is 24 mA. If 80% of electrons reach collector its base current in mA is
  • 36
  • 26
  • 16
  • 6
A NPN transistor conducts when
  • Both collector and emitter are positive with respect to the base
  • Collector is positive and emitter is negative with respect to the base
  • Collector is positive and emitter is at same potential as the base
  • Both collector and emitter are negative with respect to the base
Which of the following is true
  • Common base transistor is commonly used because current gain is maximum
  • Common emitter is commonly used because current gain is maximum
  • Common collector is commonly used because current gain is maximum
  • Common emitter is the least used transistor
A transistor is operated in common-emitter configuration at Vc = 2V such that a change in the base current from 100 μA to 200 μA produces a change in the collector current from 5 mA to 10 mA. The current gain is
  • 75
  • 100
  • 150
  • 50

Physics-Semiconductor Devices-88269.png
  • 12
  • 24
  • 6
  • 5
In a PNP transistor working as a common-base amplifier, current gain is 0.96 and emitter current is 7.2mA. The base current is
  • 0.4 mA
  • 0.2 mA
  • 0.29 mA
  • 0.35 mA
In a common emitter transistor, the current gain is 80. What is the change in collector current, when the change in base current is 250 μA
  • 80 × 250 μA
  • (250 – 80)μA
  • (250 + 80)μA
  • 250/80μA
For a transistor the parameter β = 99. The value of the parameter α is
  • 0.9
  • 0.99
  • 1
  • 9
For transistor action
I. Base, emitter and collector regions should have similar size and doping concentrations
II. The base region must be be very thin and lightly doped
III. The emitter-base junction is forward biased and base-collector junction is reverse biased
IV. Both the emitter-base junction as well as the base collector junction are forward biased
Which one of the following pairs of statements is correct
  • IV, I
  • I, II
  • II, III
  • III, IV
An NPN-transistor circuit is arranged as shown in figure. It is
Physics-Semiconductor Devices-88274.png
  • A common base amplifier circuit
  • A common emitter amplifier circuit
  • A common collector amplifier circuit
  • Neither of the above
In case of NPN–transistors the collector current is always less than the emitter current because
  • Collector side is reverse biased and emitter side is forward biased
  • After electrons are lost in the base and only remaining ones reach the collector
  • Collector side is forward biased and emitter side is reverse biased
  • Collector being reverse biased attracts less electrons
In a transistor circuit shown here the base current is 35 μA. The value of the resistor Rb is
Physics-Semiconductor Devices-88278.png
  • 123.5 k Ω
  • 257 k Ω
  • 380.05 k Ω
  • None of these
Which of these is unipolar transistor?
  • Point contact transistor
  • Field effect transistor
  • PNP transistor
  • None of the above
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