Electronics and Communication Book Back Questions & Answers
Unit 10 > Physics > Class 12 > Samacheer Kalvi - English Medium
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1. The barrier potential of a silicon diode is approximately,
a) 0.7 V
b) 0.3V
c) 2.0 V
d) 2.2V
Correct answer: a) 0.7 V
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2. Doping a semiconductor results in
a) The decrease in mobile charge carriers
b) The change in chemical properties
c) The change in the crystal structure
d) The breaking of the covalent bond
Correct answer: c) The change in the crystal structure
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3. In an unbiased p-n junction, the majority charge carriers (that is, holes) in the p-region diffuse into n-region because of
a) the potential difference across the p-n junction
b) the higher hole concentration in p-region than that in n-region
c) the attraction of free electrons of n-region
d) the higher concentration of electrons in the n-region than that in the p-region
Correct answer: d) the higher concentration of electrons in the n-region than that in the p-region
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4. The zener diode is primarily used as
a) Rectifier
b) Amplifier
c) Oscillator
d) Voltage regulator
Correct answer: d) Voltage regulator
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5. The principle based on which a solar cell operates is
a) Diffusion
b) Recombination
c) Photovoltaic action
d) Carrier flow
Correct answer: c) Photovoltaic action
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6. The light emitted in an LED is due to
a) Recombination of charge carriers
b) Reflection of light due to lens action
c) Amplification of light falling at the junction
d) Large current capacity.
Correct answer: a) Recombination of charge carriers
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7. The barrier potential of a p-n junction depends on i) type of semiconductor material ii) amount of doping iii) temperature. Which one of the following is correct?
a) (i) and (ii) only
b) (ii) only
c) (ii) and (iii) only
d) (i) (ii) and (iii)
Correct answer: d) (i) (ii) and (iii)
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8. To obtain sustained oscillation in an oscillator,
a) Feedback should be positive
b) Feedback factor must be unity
c) Phase shift must be 0 or 2
d) All the above
Correct answer: d) All the above
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9. If the input to the NOT gate is A = 1011, its output is
a) 0100
b) 1000
c) 1100
d) 0011
Correct answer: a) 0100
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10. The given electrical network is equivalent to
a) AND gate
b) OR gate
c) NOR gate
d) NOT gate
Correct answer: c) NOR gate
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11. The output of the following circuit is 1 when the input ABC is
a) 101
b) 100
c) 110
d) 010
Correct answer: a) 101
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12. The frequency range of 3 MHz to 30 MHz is used for
a) Ground wave propagation
b) Space wave propagation
c) Sky wave propagation
d) Satellite communication
Correct answer: c) Sky wave propagation