1. Select the incorrect statement from the following option.
a) Nitinol is a non-magnetic material
b) It has a shape memory strain of about 8.5%
c) It has lower ductility than other shape memory alloys like Au-Cd
d) It possess excellent corrosion resistant
Explanation: Nitinol has a higher ductility than other shape memory alloys like Au-Cd and can freely revert back to its original shape. All the other options are correct. It is a non-magnetic material and possess excellent corrosion resistant.
2. The materials which offer no resistance to the passage of electricity are ___________
a) Superconductors
b) Semiconductors
c) Optical fibre
d) Smart material
Explanation: Superconductors offer no resistance to the passage of electricity. Semi-conductor is a substance, usually a solid chemical element or compound, that can conduct electricity under some conditions but not others, making it a good medium for the control of electrical current.
3. The critical temperature for the cuprate La2CuO4 is ___________
a) 40 K
b) 90 K
c) 125 K
d) 35 K
Explanation: The critical temperature for the cuprate La2CuO4 is 35 K. Cuprate loosely refers to a material that can be viewed as containing copper anions.
4. Identify the class of the superconductor to which TiO and NbO belong.
a) Simple compounds
b) Nonstoichiometric crystals having defects
c) Charge-transfer compounds
d) Molecular crystals
Explanation: TiO and NbO are the examples of non-stoichiometric crystals having defects class of superconductors.
5. The dielectric material that shows spontaneous and reversible dielectric polarisation are ___________
a) Piezoelectrics
b) Pyroelectrics
c) Ferroelectrics
d) None of the mentioned
Explanation: Piezoelctrics are those dielectric materials in which pressure can produce an electrical response and electrical forces produce a mechanical response. Pyroelectrics are those dielectric in which polarisation changes with temperature. Ferroelectrics are those dielectric materials that show spontaneous and reversible dielectric polarisation.
6. What is the principle on which an optical fibre works?
a) Total internal reflection
b) Farraday’s law of induction
c) Doppler Effect
d) Hooke’s law
Explanation: Due to total internal reflection, light can be transmitted over many kilometers without any appreciable decrease in the intensity by optical fibres.
7. Optical fibre can be safely used for signal transmission near the nuclear installation because ___________
a) There is no leakage of signals
b) Plastic cladded silica fibres are resistant to nuclear radiations
c) Plastic cladded silica fibres are not resistant to nuclear radiations
d) There is no electromagnetic interference
Explanation: Optical fibre can be safely used for signal transmission near the nuclear installation because the plastic cladded silica fibres are resistant to nuclear radiation. Due to total internal reflection, light can be transmitted over many kilometers without any appreciable decrease in the intensity of optical fibres.
8. The correct sequence for the procedure adopted for making a pure elemental semiconductor consist of ___________
a) Preparation of ultrapure Si or Ge >> Doping >> Preparation of single crystals of Si or Ge
b) Doping >> Preparation of ultrapure Si or Ge >> Preparation of single crystals of Si or Ge
c) Preparation of ultrapure Si or Ge >> Preparation of single crystals of Si or Ge >> Doping
d) Preparation of single crystals of Si or Ge >> Preparation of ultrapure Si or Ge >> Doping
Explanation: The correct sequence for the procedure adopted for making a pure elemental semiconductor consist of: Preparation of ultrapure Si or Ge>> Preparation of single crystals of Si or Ge>> Doping
9. Which of the following is not an application of a transistor?
a) Tunnel diodes
b) Thermistors
c) Amplifiers
d) None of the mentioned
Explanation: All the mentioned options are the applications of a transistor. A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power. It is used for tunnel diodes, thermistors and amplifiers.
10. The amplification factor for transistor when used as an amplifier will be ___________
a) 25
b) 50
c) 75
d) 100
Explanation: The amplification factor for transistor when used as an amplifier will be 50. Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive.