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Set 7 of 17 · Questions 181-210 of 501

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JEE Main Physics · Semiconductor Devices · Set 7 (Q181-210)

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  1. 181.
    When a semiconductor is doped with donor impurity
    1. (1)the hole concentration decreases and electron concentration increases
    2. (2)the hole concentration increases and electron concentration decreases.
    3. (3)both hole concentration and electron concentration increase
    4. (4)both hole concentration and electron concentration decrease
  2. 182.
    Carbon, silicon and germanium have four valence electrons each. These are characterized by valence and conduction bands separated by energy band gap respectively equal to and . Which of the following statements is true? [2005]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  3. 183.
    For a transistor and are given as and . Then the correct relation between and will be:
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  4. 184.
    The radius of germanium (Ge) nuclide is measured to be twice the radius of . The number of nucleons in Ge are [2006]
    1. (1)73
    2. (2)74
    3. (3)75
    4. (4)72
  5. 185.
    In a transistor, a change of 8.0 in the emitter current produces a change of 7.8 in the collector current. What change in the base current is necessary to produce the same change in the collector current [2011]
    1. (1)50
    2. (2)100
    3. (3)150
    4. (4)200
  6. 186.
    The energy gap of an LED is . When the LED is switched 'ON', the momentum of the emitted photons is
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  7. 187.
    An amplifier has a voltage gain . The voltage gain in is [2006]
    1. (1)20 dB
    2. (2)60 dB
    3. (3)3 dB
    4. (4)30 dB
  8. 188.
    In a transistor circuit, if emitter and collector connections are interchanged then
    1. (1)emitter current will increase.
    2. (2)base current decreases.
    3. (3)collector current increases.
    4. (4)no current flows in the circuit.
  9. 189.
    A junction diode can withstand upto current under forward bias. The diode has a potential difference of across it, which is assumed to be independent of current. What is the maximum voltage of the battery used to forward bias the diode when a resistance of is connected in series with it?
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  10. 190.
    When the transistor is used as an amplifier
    1. (1)Emitter-base junction must be reverse biased, Collector-base junction must be forward biased.
    2. (2)Emitter-base junction must be forward biased, Collector-base junction must be forward biased.
    3. (3)Emitter-base junction must be reverse biased, Collector-base junction must be reverse biased.
    4. (4)Emitter-base junction must be forward biased, Collector-base junction must be reverse biased.
  11. 191.
    In a full wave rectifier in which input voltage is represented by , then peak inversion voltage ofnon‐conducting diode will be [2018]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  12. 192.
    The current gain for a transistor working as a common‐ base amplifier is 0.96. If the emitter current is 7.2 mA, Ll1e base current will be [2001]
    1. (1)0.42 mA
    2. (2)0.49 mA
    3. (3)0.35 mA
    4. (4)0.29 mA
  13. 193.
    Choose the only false statement from the following [2005]
    1. (1)Substances with energy gap of the order of 10 eV are insulators
    2. (2)The conductivity of a semiconductor increases with increase in temperature
    3. (3)In conductors the valence and conduction bands may overlap
    4. (4)The resistivity of a semiconductor increases with increase in temperature
  14. 194.
    For sky wave propagation of 10 MHz signal, what should be the minimum electron density in ionosphere? [2005]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  15. 195.
    Out of the following, which one is a forward biased diode? [NEET 2020]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  16. 196.
    For transistor, the current ratio ' ' is defined the ratio of
    1. (1)collector current to emitter current
    2. (2)collector current to base current
    3. (3)base current to collector current
    4. (4)emitter current to collector current
  17. 197.
    Copper has face centered cubic lattice with interatomic spacing equal to 2.54 A. The value of the lattice constant for this lattice is [2005]
    1. (1)1.27
    2. (2)5.08 A
    3. (3)2.54
    4. (4)3.59 A
  18. 198.
    For a transistor, and are the current ratios, then value of is
    1. (1)1
    2. (2)1.5
    3. (3)2
    4. (4)2.5
  19. 199.
    The band gap in a semi-conductor is . The maximum wavelength of electromagnetic radiation which can create a hole-electron pair in this semiconductor is equal to [Use ]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  20. 200.
    Which one of the following represents forward bias diode? [NEET 2017]
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  21. 201.
    An intrinsic semiconductor is converted into n-type extrinsic semiconductor by doping it with [NEET 2020]
    1. (1)phosphorus
    2. (2)aluminium
    3. (3)silver
    4. (4)germanium
  22. 202.
    If a small amount of antimony is added to germanium crystal [2011]
    1. (1)the antimony becomes an acceptor atom
    2. (2)there will be more free electrons than holes in the semiconductor
    3. (3)its resistance is increased
    4. (4)it becomes a p‐type semiconductor
  23. 203.
    When the temperature of a semiconductor increases then
    1. (1)number of free electrons only increases
    2. (2)number of holes only increases
    3. (3)both number of free electrons and number of holes increase
    4. (4)both number of free electrons and number of holes decrease
  24. 204.
    In common base circuit of a transistor, current amplification factor is 0.95 . Calculate the emitter current if base current is .
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  25. 205.
    If an emitter current is changed by , the collector current changes by . The value of will be –
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  26. 206.
    For an to emit light in visible region of the electromagnetic spectrum, it can have energy band gap in the range of, (Plank's constant, and speed of light, in vacuum)
    1. (1) to
    2. (2) to
    3. (3) to
    4. (4) to
  27. 207.
    If the ratio of electron and hole currents in a semiconductor is and the ratio of drift velocities of electrons and holes is , then ratio of concentrations of electrons and holes will be
    1. (1)
    2. (2)
    3. (3)
    4. (4)
  28. 208.
    A reverse biased Zener diode when operated in the breakdown region works as
    1. (1)an amplifier
    2. (2)an oscillator
    3. (3)a voltage regulator
    4. (4)a rectifier
  29. 209.
    A voltage regulating circuit consisting of Zener diode, having break-down voltage of 10 V and maximum power dissipation of 0.4 W , is operated at 15 V . The approximate value of protective resistance in this circuit is .
  30. 210.
    A transistor is used in common-emitter mode in an amplifier circuit. When a signal of 10 mV is added to the base-emitter voltage, the base current changes by and the collector current changes by 1.5 mA . The load resistance is . The voltage gain of the transistor will be .