JEE Physics Semiconductor Electronics MCQs Set B

Question. A transistor cannot be used as an
(a) Rectifier
(b) Modulator
(c) Oscillator
(d) Amplifier

Answer: A

Question. Which of the following pn junction is not used in reverse bias?
(a) Both
(b) Solar cell
(c) LED
(d) None of these

Answer: A

Question. A crystal has bcc structure and its lattice constant is 3.6 Å. What is the atomic radius?
(a) 1.56 Å
(b) 1.27 Å
(c) 1.8 Å
(d) 3.6 Å

Answer: A

Question. In an n-p-n transistor working in active mode, the depletion region
(a) At emitter-base junction is thinner than that at collector-base junction
(b) At the two junctions have equals width
(c) At emitter-base junction is wider than that at collector-base junction
(d) Is not formed

Answer: A

Question. 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
(a) 5 × 10¹⁴ Hz
(b) 1 × 10¹⁴ Hz
(c) 10 × 10¹⁴ Hz
(d) 20 × 10¹⁴ Hz

Answer: A

Question. The cations and anions are arranged in alternate form in
(a) Ionic crystal
(b) Covalent crystal
(c) Semi-conductor crystal
(d) Metallic crystal

Answer: A

Question. In semiconductors at room temperature
(a) The valence band is partially empty and the conduction band is partially filled
(b) The valence band is completely filled and the conduction band is partially filled
(c) The valence band is completely filled
(d) The conduction band is completely empty

Answer: A

Question. Which one of the following bonds produces a solid that reflects light in the visible region and whose electrical conductivity decreases with temperature and has high melting point?
(a) Metallic bonding
(b) Covalent bonding
(c) Ionic bonding
(d) van der Waal's bonding

Answer: A

Question. In good conductors of electricity, the type of bonding that exists is
(a) Metallic
(b) van der Waal’s
(c) Ionic
(d) Covalent

Answer: A

Question. In an insulator, the forbidden energy gap between the valence band and conduction band is of the order of
(a) 5 eV
(b) 1 eV
(c) 0.1 MeV
(d) 1 MeV

Answer: A

Question. A p-n junction has a depletion layer thickness of the order of
(a) 10^–6 m
(b) 10^–4 m
(c) 10^–8 m
(d) 10^–10 m

Answer: A

Question. If a small amount of antimony is added to germanium crystal
(a) There will be more free electrons than hole in the semiconductor
(b) The antimony becomes an acceptor atom
(c) It becomes a p-type semiconductor
(d) Its resistance is increased

Answer: A

Question. In forward biasing of the p-n junction
(a) The positive terminal of the battery in connected to p-side and the depletion region becomes thin
(b) The positive terminal of the battery is connected to p-side and the depletion region becomes thick
(c) The positive terminal of the battery is connected to n-side and the depletion region becomes thin
(d) The positive terminal of the battery is connected to n-side and the depletion region becomes thick

Answer: A

Question. In a reverse-biased p-n junction, when the applied bias voltage is equal to the breakdown voltage, then
(a) Voltage remains constant while current increases sharply
(b) Current remains constant while voltage increase sharply
(c) Current and voltage increase
(d) Current and voltage decrease

Answer: A

Question. When arsenic is added as an impurity to silicon, the resulting material is
(a) n-type semiconductor
(b) p-type semiconductor
(c) p-type conductor
(d) n-type conductor

Answer: A

Question. To obtain a p-type germanium semiconductor, it must be doped with
(a) Indium
(b) Phosphorus
(c) Arsenic
(d) Antimony

Answer: A

Question. The cause of the potential barrier in a p-n diode is
(a) Concentration of positive and negative charges near the junction
(b) Depletion of positive charges near the junction
(c) Concentration of positive charges near the junction
(d) Depletion of negative charges near the junction

Answer: A

Question. A semi-conducting device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be
(a) A p-n junction
(b) A p-type semi-conductor
(c) An intrinsic semi-conductor
(d) An n-type semi-conductor

Answer: A

Question. A p-n junction diode can be used as
(a) Rectifier
(b) Amplifier
(c) Oscillator
(d) Condenser

Answer: A

Question. In a p-type semiconductor, the majority carriers of current are
(a) Holes
(b) Neutrons
(c) Electrons
(d) Protons

Answer: A

Question. In forward bias, the width of potential barrier in a p-n junction diode
(a) Decreases
(b) Increases
(c) Remains constant
(d) Immobile ions

Answer: A

Question.  Depletion layer consists of
(a) Immobile ions
(b) Electrons
(c) Protons
(d) Mobile ions

Answer: A

Question. In a junction diode, the holes are due to
(a) Missing of electrons
(b) Protons
(c) Neutrons
(d) Extra electrons

Answer: A

Question. In a PN junction
(a) High potential at N side and low potential at P side
(b) High potential P side and low potential at N side
(c) P and N both are at same potential
(d) Undetermined

Answer: A

Question. Reverse bias applied to a junction diode
(a) Raises the potential barrier
(b) Increases the minority carrier current
(c) Increases the majority carrier current
(d) Lowers the potential barrier

Answer: A

Question. Barrier potential of a p-n junction diode does not depend on
(a) Diode design
(b) Temperature
(c) Forward bias
(d) Doping density

Answer: A

Question. In a p-n junction photo cell, the value of the photo-electromotive force produced by monochromatic light is proportional to
(a) The intensity of the light falling on the cell
(b) The voltage applied at the p-n junction
(c) The barrier voltage at the p-n junction
(d) The frequency of the light falling on the cell

Answer: A

Question. Choose the only false statement from the following
(a) The resistivity of a semiconductor increases with increase in temperature
(b) The conductivity of a semiconductor increases with increase in temperature
(c) Substances with energy gap of the order of 10 eV are insulators
(d) In conductors the valence and conduction bands overlap

Answer: A

Question. Zener diode is used as
(a) Stabilisation
(b) Amplification
(c) Rectification
(d) Producing oscillations in an oscillator

Answer: A

Question. Application of a forward bias to a p-n junction
(a) Increases the diffusion of conduction electrons from n side to p side
(b) Increases the electric field in the depletion zone
(c) Increases the potential difference across the depletion zone
(d) Widens the depiction zone

Answer: A

Question. In a zener diode, break down occurs in reverse bias due to
(a) Internal field emission
(b) All of these
(c) Impact ionisation
(d) High doping concentration

Answer: A

Question. A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength
(a) 4000 Å
(b) 4000 nm
(c) 6000 Å
(d) 6000 nm

Answer: A

Question.  In a p-n junction, depletion region contains
(a) Equal number of donor and acceptor ions
(b) No charges at all
(c) Equal number of conduction electrons and holes
(d) More conduction holes than electrons

Answer: A

Question. C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator whereas Si is intrinsic semiconductor. This is because
(a) The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third
(b) The four bonding electrons in the case of C lie in the third orbit, whereas for Si they lie in the fourth orbit
(c) In case of C the valance band is not completely filled at absolute zero temperature
(d) In case of C the conduction band is partly filled even at absolute zero temperature

Answer: A