1.In a semiconductor, the Question 6.
(b) binary numbers
forbidden energy gap between The Voltage gain is highest for (c) logic
the valence band and the (a) common emitter amplifier (d) truth
(b) common base amplifier
conduction band is of the order
(c) common collector amplifier.
of: (d) Equal in all the three. Answer C
(a) 1 Mev Question 12.
(b) 1 ev The following logic symbol is
(c) 0.1 Mev Answer A equivalent to:
Question 7.
(d) 5ev
In an n-p-n transistor circuit the
collector current is 18 mA. If
Answer: (b) 1 ev 90% of the electrons emitted
reach the collector, than the
2. emitter current is:
If the conductivity of a (a) 1.6 mA (a) AND gate
semiconductor is only due to (b) 16.4 mA (b) OR gate
break of the covalent band due (c) 18 mA (c) NOT gate
to the thermal excitation, then (d) 20 mA (d) NAND gate
the semiconductor is called:
(a) intrinsic
(b) extrinsic Answer C Answer A
(c) Acceptor Question 8. Question 13.
(d) none of these In the common emitter amplifier, Which of the following gates
the phase difference between corresponds to the truth table
the input voltage and output given here:
Answer A voltage signal across the
Question 3. collector and emitter is:
In a good conductor, the energy (a) 0
levels in a valence band:
(a) are partially filled only.
(b) overlap with conduction band (b)
only. (c) π
(c) both (a) and (b) are correct.
(d) none of these (d)
AnswerC (a) NAND
Question 9. (b) OR
Answer C (c) NOR
Question 4. In common base amplifier, the
phase difference between the (d) AND
A hole in a p-type semiconductor
is- input and output voltage signal is
(a) an excess electron (a) 0
Answer A
(b) A missing atom Question 14.
(c) A missing electron (b) The conductivity of
(d) A donor level. Answer C semiconductors like Ge and Si:
(a) increases when it is doped
(c) with pentavalent impurity.
Question 5. (d) π
(b) increases when it is doped
The mobility of conduction AnswerA with trivalent impurity.
electrons is greater than that of Question 10. (c) increases when it is doped
holes since electrons is greater The part of the transistor which with pentavalent or trivalent
than that of holes since is heavily doped to produce a
impurity.
electrons. large number of majority carriers (d) none
(a) are negatively charged. is:
(b) are lighter (a) emitter
(c) require smaller energy for (b) base Answer C
moving through the crystal (c) collector Question 15.
lattice. (d) none Answer A In which case is the junction
(d) Undergo smaller number of
collisions.
Question 11.
In principle, Boolean algerbra is
Answer C based on:
(a) simple numbers
diode forward biased. emitter configuration. For a Answer: (b)
change of 6 mA in base current.
Change in collector current is
(a) 4.8 mA
4 In semiconductors, at room
(b) 6 mA temperature
(b) 8 mA (a) the conduction band is
(d) 24 mA completely empty
(b) the valence band is partially
empty and the conduction band
Answer D
is partially filled
Question 21.
Answer B A truth table is given below.
(c) the valence band is
Question 16. Which of the following has this completely filled and the
Assuming that the junction diode type of truth table? conduction band is partially
is ideal, the current in the filled
arrangement shown here is: (d) the valence band is
completely filled
Answer: (b)
(a) 2 mA (a) XOR gate
(b) 30 mA (b) NOR gate
(b) AND gate
5 Barrier potential of a P-N
(c) 20 mA
(d) 10 mA (d) OR gate Answer B junction diode does not
Answer C depend on
Question 17. (a) doping density
An oscillator is an amplifier with: 1 A p-type semiconductor is
(a) a large gain (a) positively charged (b) diode design
(b) Negative feedback (b) negatively charged (c) temperature
(c) positive feedback (c) uncharged
(d) no feedback (d) uncharged at 0K but charged
at higher temperatures (d) forward bias
AnswerC
Question 18. Answer: (c) Answer: (b)
How many AND gates are
required to form, NAND gate? 6 If the two ends of a p-n
(a) 0
2 Number of electrons in the
junction are joined by a wire
(b) 1 valence shell of a pure
(a) there will not be a steady
(c) 2 semiconductor is
(a) 1 current in the circuit
(d) 4
(b) there will be a steady current
from the n-side to the p side
Answer B
(b) 2 (c) there will be a steady current
Question 19. from the p-side to the n side
Which of following statements is (c) 3 (d) there may or may not be a
not true? current depending upon the
(a) Resistance of an intrinsic resistance of the connecting wire
(d) 4
semiconductor decreases with
increase in temperature.
(b) Doping pure Si with trivalent Answer: (d) Answer: (a)
impurities gives p-type
semiconductor. 7 Forward biasing is that in
3 In a half wave rectifier, the
(c) The majority carriers in n-
r.m.s. value of the a.c. which applied voltage
type semiconductor are holes.
(d) A p-n junction can act as component of the wave is (a) increases potential barrier
semiconductor diode. (a) equal to d.c. value (b) cancels the potential barrier
(c) is equal to 1.5 volt
(b) more than d.c. value (d) None of these
Answer C
Question 20. (c) less than d.c. value
For a transistor, current Answer: (b)
amplification factor is 0.8. The (d) zero
transistor is changed to common
8 When p-n junction diode is Answer: The surface of from …………………. when it
forward biased then contact of p-type and n-type is forward biased.
(a) both the depletion region and crystal.
barrier height are reduced
(b) the depletion region is Answer
widened and barrier height is Answer: p to n region.
reduced
(c) the depletion region is
reduced and barrier height is
increased Question 2.
(d) Both the depletion region The thickness of the
and barrier height are increased depletion layer is of the order
Question 6.
of ………………….
The zener voltage can have
Answer: (a)
value from ………………….
Answer to …………………. volts.
9 Filter circuit -6
Answer: 1 µm = 10 m.
(a) eliminates a.c. component
(b) eliminates d.c. component Answer
(c) does not eliminate a.c. Answer: 1V, several hundred.
component
(d) None of these
Answer: (a) Question 3.
The potential barrier for S1 is
10 Bridge type rectifier uses about …………………. and
(a) four diodes Question 7.
the electric field across the
junction is about The arrow in the symbol of a
…………………. transistor shows the direction
(b) six diodes
………………….
Answer
3 -1
(c) two diodes Answer: 0.7V, 7 × 10 Vm
Answer
(d) one diode Answer: Conventional current
or hole current.
Answer: (a)
11 What is the resistivity of a Question 4.
pure semiconductor at The width of the depletion
absolute zero ? layer and the potential barrier
(a) Zero across the junction Question 8.
(b) Infinity …………………. due to Below knee voltage, the
(c) Same as that of conductors at reverse biasing. variation of current in the p-n
room temperature junction is ………………….
(d) Same as that of insulators at and above it, it is
room temperature Answer
Answer: increases. ………………….
Answer: (b)
Answer
Answer: non-linear, linear
Fill in the Blanks
Question 1.
…………………. is called as
junction in p-n junction diode.
Question 5.
The direction of conventional
Answer current in a p-n junction is
