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Semiconductor Electronics · Question 67

AIPMT 2011 (Prelims)MCQEasy📈 Topic in 0% papers+4−1
1

If a small amount of antimony is added to germanium crystal

  1. it becomes a p-type semiconductor
  2. the antimony becomes an acceptor atom
  3. there will be more free electrons than holes in the semiconductor
  4. its resistance is increased

Answer

(3) there will be more free electrons than holes in the semiconductor

Solution

Antimony (Sb) is pentavalent (group 15) and germanium is tetravalent.

Four valence electrons of Sb form covalent bonds with Ge atoms; the fifth electron becomes free.

Sb acts as a donor and the crystal becomes n-type, with ne nh (more free electrons than holes); its conductivity increases, i.e. resistance decreases.

Answer: (3)

AIPMT 2011 (Prelims)

Keep practising — Semiconductor Electronics

2

A transistor is operated in common emitter configuration at VC = 2 V such that a change in the base current from 100 A to 300 A produces a change in the collector current from 10 mA to 20 mA. The current gain is

  1. 50
  2. 75
  3. 100
  4. 25
Out of syllabusAIPMT 2011 (Prelims)
3

The following figure shows a logic gate circuit with two inputs A and B and the output Y. The voltage waveforms of A, B and Y are as given. [figure] The logic gate is

  1. NOR gate
  2. OR gate
  3. AND gate
  4. NAND gate
AIPMT 2010 (Mains)
4

For transistor action Which one of the following pairs of statements is correct?

  1. D and A
  2. A and B
  3. B and C
  4. C and D
Out of syllabusAIPMT 2010 (Mains)
5

To get an output Y = 1 in given circuit which of the following input will be correct? [figure]

  1. A 1, B 0, C 0
  2. A 1, B 0, C 1
  3. A 1, B 1, C 0
  4. A 0, B 1, C 0
AIPMT 2010 (Prelims)
6

Which one of the following statements is false?

  1. Pure Si doped with trivalent impurities gives a p-type semiconductor.
  2. Majority carriers in a n-type semiconductor are holes.
  3. Minority carriers in a p-type semiconductor are electrons.
  4. The resistance of intrinsic semiconductor decreases with increase of temperature.
AIPMT 2010 (Prelims)
7

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?

  1. metallic bonding
  2. van der Waals' bonding
  3. ionic bonding
  4. covalent bonding
AIPMT 2010 (Prelims)
8

The device that can act as a complete electronic circuit is

  1. junction diode
  2. integrated circuit
  3. junction transistor
  4. zener diode
AIPMT 2010 (Prelims)
9

A common emitter amplifier has a voltage gain of 50, an input impedance of 100 and an output impedance of 200 . The power gain of the amplifier is

  1. 500
  2. 1000
  3. 1250
  4. 50
Out of syllabusAIPMT 2010 (Prelims)
10

A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength

  1. 4000 nm
  2. 6000 nm
  3. 4000 A
  4. 6000 A
AIPMT 2009
11

The symbolic representation of four logic gates are given below [figure] The logic symbols for OR, NOT and NAND gates are respectively

  1. (iv), (i), (iii)
  2. (iv), (ii), (i)
  3. (i), (iii), (iv)
  4. (iii), (iv), (ii)
AIPMT 2009

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