CBSE Questions for Class 12 Engineering Physics Semiconductor Electronics: Materials,Devices And Simple Circuits Quiz 4 - MCQExams.com

The thickness of the depletion region is of the order of ___________ of a micrometre.
  • one-hundredth
  • one-tenth
  • one-thousandth
  • None of these
The zone in a semiconductor diode where no free charge carriers exists is known as the:
  • anode region
  • cathode region
  • depletion region
  • None of these
Two important processes that occur during the formation of a p-n junction.
  • Diffusion
  • Drift
  • Both drift and diffusion
  • Drift in p region and diffusion in n region
Which of these is the best description of a Zener diode ?
  • It is a constant voltage device.
  • It operates in the reverse region.
  • It is a constant current device.
  • It works in forward region.
Which among the following devices work on the basis of photo-voltaic effect?
  • Photo-diode
  • Light Emitting Diode (LED)
  • Solar Cell
  • None of these
The creation of voltage or electric current in a material upon exposure to light is termed as 
  • photo-ionic effect
  • thermi-ionic effect
  • photo-voltaic effect
  • None of these.
In a photo-diode, 
  • photocurrent is proportional to incident light intensity
  • photocurrent is inversely proportional to incident light intensity
  • photocurrent is independent of the incident light intensity
  • incident light intensity is proportional to the photocurrent
The inputs to the digital circuit are shown below. The output Y is.

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  • $$A+B+\bar{C}$$
  • $$(A+B)\bar{C}$$
  • $$\bar{A}+\bar{B}+\bar{C}$$
  • $$\bar{A}+\bar{B}+{C}$$
If the bandgap between valence band and conduction band in a material is $$0 eV$$, then the material is
  • Semiconductor
  • Good conductor
  • Superconductor
  • Insulator
In an LED device, the intensity of emitted light 
  • increases continuously with the forward current of the diode.
  • increases continuously with the forward current of the diode, reaches a maximum and then decreases.
  • decreases continuously with the forward current of the diode.
  • decreases continuously with the forward current of the diode, reaches a minimum and then increases.
An intrinsic semiconductor is:
  • undoped
  • doped
  • can be undoped or doped
  • semi-doped
LEDs have the following advantages over conventional incandescent low power lamps: 
  • Long life and ruggedness.
  • Low operational voltage and less power
  • Fast on-off switching capability.
  • All of the above 
In which of the following statements, the obtained impure semiconductor is of p-type?
  • Germanium is doped with bismuth
  • Silicon is doped with antimony
  • Germanium is doped with gallium
  • Silicon is doped with phosphorus
In intrinsic semiconductors:
  • $$n>p$$
  • $$p>n$$
  • $$n=p$$
  • $$n=0$$
Which of the following is an example of a direct band gap intrinsic semiconductor?
  • Silicon
  • Germanium
  • Gallium Arsenide
  • none of these
Holes are created when:
  • electric discharge causes damage to semicondcutors
  • there are too many electrons
  • a co-valent bond is broken due to thermal energy, the removal of one electron leaves a vacancy
  • none of these
Which of the following statement(s) is/are true about holes?
  • They flow from positive terminal to negative terminal
  • They flow from negative terminal to positive terminal
  • They do not flow
  • None of these
In N-type semiconductors, holes are:
  • majority carriers
  • minority carriers
  • absent
  • none of these
In intrinsic semiconductors,:
  • holes or electrons are supplied by a foreign atom acting as an impurity
  • holes in the valence band are vacancies created by electrons that have been thermally excited to the conduction band
  • has high amount of impurities
  • none of the above
For one electron vacancy,
  • no holes are created
  • 1 hole is created
  • 2 holes are created
  • 4 holes are created
In p-type semiconductors, holes are:
  • majority carriers
  • minority carriers
  • absent
  • none of the above
Diode can work as
  • Modulator
  • Demodulator
  • Rectifier
  • Amplifier
 A semiconductor device is connected in a series circuit with a battery and resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be
  • a p-type semiconductor
  • an n-type semiconductor
  • a p-n junction
  • an intrinsic semiconductor
When an impurity is doped into semiconductor, the conductivity of the semiconductor 
  • increases
  • decreases
  • remains same
  • becomes zero
Which of the following is/are correct about the direction of holes/electron?
  • Holes are moving along the direction of electric field.
  • Electrons are moving along the direction of electric field.
  • Electrons are moving against the direction of electric field.
  • None of the above
In the valance band, the current is due to 
  • the presence of electrons
  • the presence of holes
  • the presence of both electrons and holes
  • none of the above
Digital circuit can be made by repetitive use of this gate-
  • AND
  • OR
  • NOT
  • NAND
State whether given statement is True or False
Resistivity of semiconductor depends on atomic nature of semiconductor.
  • True
  • False
The concepts of holes is introduced based on 
  • the notion that it is a whole lot easier to keep track of the missing particles in an "almost-full" band
  • the keeping track of the actual electrons in that band
  • the charge of holes
  • none of the above
In physics, chemistry, and electronic engineering, _______________ is the lack of an electron at a position where one could exist in an atom or atomic lattice.
  • an electron hole
  • electron
  • proton
  • neutron
A semiconductor is a material with a small but non-zero band gap that behaves as an insulator at absolute zero but allows thermal excitation of electrons into its ____________ at temperatures that are below its melting point.
  • HOMO
  • valence band
  • conduction band
  • LUMO
The relationship between band gap energy and temperature can be described by ____________.
  • supersymmetric quantum mechanics.
  • hyperuniformity.
  • phonons theory.
  • Varshni's empirical expression.
What will be the input of $$A$$ and $$B$$ for Boolean expression
597538.png
  • $$0,0$$
  • $$0,1$$
  • $$1,0$$
  • $$1,1$$
The ________________ determines how electrons respond to forces (via the concept of effective mass).
  • electrostatic forces
  • dispersion relation
  • magnetic force
  • lorentz force
Which of the following cannot be used in electronic devices?
  • Aluminium gallium arsenide
  • Indium gallium arsenide
  • Gallium arsenide
  • Quasicrystals.
The output of AND gate is ____________.
  • $$Y=A\cdot B$$
  • $$Y=A+B$$
  • $$Y=\overline{A+B}$$
  • $$Y=\overline{A\cdot B}$$
When a hole is produced in P-type semiconductor, there is 
  • Extra electron in valence band
  • Extra electron in conduction band
  • Missing electron in valence band
  • Missing electron in conduction band
The conductivity of intrinsic semiconductor decreases with increase in temperature.
  • True
  • False
Zener-diode is used in.
  • Amplification
  • Rectification
  • Oscillator in producing oscillations
  • Volatge regulation
The transducer used in television transmission works on the principle of
  • Electromagnetic induction
  • Photoelectric effect
  • Raman's effect
  • Rayleigh's effect
In an experiment of photoelectric effect the number of photoelectrons has to be increased without changing their frequency. The suitable step to be taken about the incident radiation for this is
  • increasing intensity without changing frequency
  • increase both frequency and intensity
  • increase frequency without increasing intensity
  • increasing only frequency
Which of the following symbol represents a universal gate?
State whether given statement is True or False
A specially designed P N junction diode converts the solar energy into electrical energy.
  • True
  • False
Which gate can be obtained by shorting both the input terminals of a NOR gate?
  • NOT
  • OR
  • AND
  • NAND
The energy gap between the valence band and the condition band for a material is $$6$$eV. The material is?
  • an insulator
  • a metal
  • an intrinsic semiconductor
  • a superconductor
Generally semiconductor can be used safely between the temperatures :
  • $$-75$$ and $$200$$
  • $$0$$ and $$75$$
  • $$-25$$ and $$300$$
  • $$-40$$ and $$1000$$
The energy gap in case of which of the following is less than $$3 eV$$?
  • Aluminium
  • Iron
  • Germanium
  • Copper
Symbolic representation of NOR gate is?
The schematic symbol of light emitting diode is (LED)
The circuit given below represents which of the logical operations?
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  • AND
  • NOT
  • OR
  • NOR
0:0:1


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