JEE Questions for Physics Semiconductor Devices Quiz 2 - MCQExams.com

n -type semiconductor is
  • positively charged
  • negatively charged
  • neutral
  • positive or negative depending upon doping material
Two diodes have resistance 20 Ω and is centre-apped with secondary voltage from centre tap to each end of secondary 50V. If external resistance is 980 Ω. What is mean load ?
  • 0.05 A
  • 45 mA
  • 0.25 A
  • 25 mA
Energy gap between valence band and conduction band of a semiconductor is
  • zero
  • infinite
  • 1 eV
  • 10 eV
Then n -type semiconductors are obtained, when germanium is doped with
  • arsenic
  • phosphorus
  • antimony
  • Any one of these
Semiconductor material having fewer free electrons than pure germanium or silicon is
  • p-type
  • n-type
  • Both (and (2)
  • None of these
If the forward voltage in a diode is increased, the width of the depletion region
  • increases
  • decreases
  • fluctuates
  • no change
At absolute zero, Si acts as
  • non-metal
  • metal
  • insulator
  • None of these
The output Y of the logic circuit given below is
Physics-Semiconductor Devices-87388.png

  • Physics-Semiconductor Devices-87389.png
  • 2)
    Physics-Semiconductor Devices-87390.png

  • Physics-Semiconductor Devices-87391.png

  • Physics-Semiconductor Devices-87392.png
The decimal number equivalent to a binary number 1011001 is
  • 13
  • 17
  • 89
  • 178
What is the number of code combination in a 4 bit byte?
  • 256
  • 4
  • 16
  • 32
How many NAND gates are required to form an AND gate ?
  • 1
  • 2
  • 3
  • 4
Identify the logic operation performed by the circuit given here
Physics-Semiconductor Devices-87393.png
  • OR
  • NOR
  • NOT
  • NAND
Any digital circuit can be realised by repetitive use of only
  • NOT gate
  • OR gate
  • AND gate
  • NOR gate
The combination of gates shown below yields
Physics-Semiconductor Devices-87395.png
  • OR gate
  • NOT gate
  • XOR gate
  • NAND gate
The figure shown the symbol of a
Physics-Semiconductor Devices-87397.png
  • AND gate
  • OR gate
  • NOT gate
  • NAND gate
In the figure, the input is across the terminals A and C and the output is across B and D. Then the output is
Physics-Semiconductor Devices-87399.png
  • zero
  • same as the input
  • full wave rectified
  • half wave rectified
Name the gate, which represents the Boolean expression
Physics-Semiconductor Devices-87400.png
  • NAND
  • AND
  • NOT
  • NOR
The binary number 10111 is equivalent to the decimal number
  • 19
  • 31
  • 23
  • 22
Digital circuit can be made by repetitive use of this gate
  • AND
  • OR
  • NOT
  • NAND
When the two inputs of a NAND gate are shorted, the resulting gate is
  • NOR
  • OR
  • NOT
  • AND

Physics-Semiconductor Devices-87403.png

  • Physics-Semiconductor Devices-87404.png
  • 2)
    Physics-Semiconductor Devices-87405.png

  • Physics-Semiconductor Devices-87406.png

  • Physics-Semiconductor Devices-87407.png
The gate for which output is high, if at least one input is low ?
  • NAND
  • NOR
  • AND
  • OR
Which logic gate is represented by the following combination of logic gates ?
  • OR
  • NOR
  • AND
  • NAND
Which of the following is not equal to 1 in Boolean algebra ?

  • Physics-Semiconductor Devices-87408.png
  • 2)
    Physics-Semiconductor Devices-87409.png

  • Physics-Semiconductor Devices-87410.png

  • Physics-Semiconductor Devices-87411.png
The term liquid crystal refers to a state that is intermediate between
  • crystalline solid and amorphous liquid
  • crystalline solid and vapour
  • amorphous liquid and its vapour
  • a crystal immersed in a liquid
The manifestation of band structure in solids is due to decreases the majority charge carrier
  • Heisenberg's uncertainty principle
  • Pauli's exclusion principle
  • Bohr's correspondence principle
  • Boitzmann's law
A solid which is not transparent to visible light and whose conductivity increases with temperature is formed by
  • ionic binding
  • covalent binding
  • van der Waals' binding
  • metallic binding
The output characteristics of an n- p-n transistor represent, (IC = collector current, VCE = potential difference between collector and emitter, IB = base current, VBB = voltage given to base, VBE = the potential difference between base and emitter)
  • changes in IC and IB and VBB are changed
  • changes in IC with changes in VCE (IB = constant)
  • changes in IB with changes in VCE
  • change in IC as VBE is changed
In a CE, n-p-n transistor circuit, the emitter current is
  • more than the collector current
  • less than the collector current
  • less than the base current
  • equal to the difference of the collector current and the base current
The current gain of a transistor in the common-base mode is 0.9. If the change in the emitter current is 5 mA, the change in the collector current will be
  • 4 mA
  • 4.5 mA
  • 5.6 mA
  • zero
If α and β are the collector emitter short circuit current amplification factor and collector base short circuit current amplification factor respectively of a transistor then α is equal to

  • Physics-Semiconductor Devices-87414.png
  • 2)
    Physics-Semiconductor Devices-87415.png

  • Physics-Semiconductor Devices-87416.png

  • Physics-Semiconductor Devices-87417.png
A common-emitter amplifier given an output of 3 V, for an input of 0.01 V. If β of the transistor is 100 and the input resistance is 1kΩ, then the collector resistance is
  • 1 kΩ
  • 3 kΩ
  • 30 kΩ
  • 30 Ω
  • 6 kΩ
In common-emitter amplifier, the current gain is 62. The collector resistance and input resistance are 5 kΩ, and 500 Ω , respectively. If the input voltage is 0.01 V, the output voltage is
  • 0.62 V
  • 6.2 V
  • 62 V
  • 620 V
  • 0.01 V
The current gain of a transistor in common-base mode is 0.995. The current gain of the same transistor in common emitter mode is
  • 197
  • 201
  • 198
  • 202
  • 199

Physics-Semiconductor Devices-87427.png
  • infinite
  • 1
  • 2
  • 0.5
  • zero
An n-p-n transistor power amplifier in CE configuration gives
  • voltage amplification only
  • currents amplification only
  • both current and voltage amplifications
  • only power gain of unity
In n-type semiconductor, electrons are majority charge carriers but it does not show any negative charge. The reason is
  • electrons are stationary
  • electrons neutralise with holes
  • mobility of electrons is extremely small
  • atom is electrically neutral
The resistance of a germanium junction diode whose V - I is shown in the figure, is (Vk = 0.3 V ).
Physics-Semiconductor Devices-87428.png
  • 5 kΩ
  • 0.2 kΩ
  • 2.3 kΩ

  • Physics-Semiconductor Devices-87429.png
In the circuit shown assume the diode to be ideal. When Vi , increases from 2V to 6 V, the change in the current is (in mA)
Physics-Semiconductor Devices-87431.png
  • zero
  • 20
  • 80/3
  • 40
In the diagram, section A represents the
Physics-Semiconductor Devices-87433.png
  • n-type germanium
  • p-type germanium
  • anode
  • diode
The bias of the p-n junction shown in the diagram is
Physics-Semiconductor Devices-87434.png
  • C to D
  • E to F
  • reverse
  • forward
The I-V characteristic of an LED is

  • Physics-Semiconductor Devices-87435.png
  • 2)
    Physics-Semiconductor Devices-87436.png

  • Physics-Semiconductor Devices-87437.png

  • Physics-Semiconductor Devices-87438.png
A diode having potential difference 0.5 V across its junction which does not depend on current, is connected in series with resistance of 20Ω across source. If 0.1 A current passes through resistance then what is the voltage of the source ?
  • 1.5 V
  • 2.0 V
  • 2.5 V
  • 5 V
A LED is constructed from a p-n junction based on a certain Ga-As-P semiconducting material whose energy gap is 1.9 eV. Identify the colour of the emitted light.
  • Blue
  • Red
  • Violet
  • Green
As shown in the figure, the current in the part of circuit is
Physics-Semiconductor Devices-87439.png
  • 0.03 A
  • 0.02 A
  • 0.04 A
  • 0.05 A
In the case of forward biasing of a p-n junction diode, which one of the following figures correctly depicts the direction of conventional current (indicated by an arrow mark)?

  • Physics-Semiconductor Devices-87441.png
  • 2)
    Physics-Semiconductor Devices-87442.png

  • Physics-Semiconductor Devices-87443.png

  • Physics-Semiconductor Devices-87444.png
In the circuit given, the current through the zener diode is
Physics-Semiconductor Devices-87445.png
  • 10 mA
  • 6.67 mA
  • 5 mA
  • 3.33 mA
  • zero
Reverse bias applied to a p-n junction diode
  • lowers the potential barrier
  • decreases the majority charge carrier
  • raises the potential barrier
  • change the mass of p-n junction diode
The contribution in the total current flowing through a semiconductor due to electrons and holes are 3/4 and 1/4 respectively. If the drift velocity of electrons is 5/2 times that of holes at this temperature, then the ratio of concentration of electrons and holes is
  • 6 : 5
  • 5 : 6
  • 3 : 2
  • 2 : 3
The forbidden energy gap in Ge is 0.72 eV. given. hc =12400 eV-Å. The maximum wavelength of radiation that will generate electron hole pair is
  • 172220 Å
  • 172.2 Å
  • 17222 Å
  • 1722 Å
0:0:1


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