Semiconductors and electronics [unit-ix]

2001

2002
Define  for a transistor. [1]
Name the bond in a solid which results due to transference of electrons from one atom to
other. [1]
What is a PN junction? With a neat circuit diagram, explain how a PN junction diode is used as a
rectifier. [2+2+6]

2003
With neat circuit diagram describe the use of n-p-n transistor as an amplifier in CE mode. [3+7]

2004
Draw the circuit of NPN transistor amplifier in CE configuration. [2]

2005
Distinguish between intrinsic and extrinsic semiconductors. [2]

2006
Give the circuit symbol of p-n-p transistor. [1]
Distinguish between p-type and n-type semiconductor. [2]
The value of  of a transistor is 49. Calculate the value of . [2]
Write short note of band theory of solids. [5]

2007
What does a rectifier circuit perform? [1]
When a pure semiconductor does behave as an insulator? [1]
With neat circuit diagrams, describe the forward and reverse biasing of a p-n junction diode.
Draw and compare their characteristics curves. [6+4]
What is a transistor? Explain with a neat circuit diagram, how it is used as an amplifier in CE
mode.
A transistor, connected in CE configuration, has input resistance 2kW. Calculate the resistance
gain and voltage gain. (Given  = 60) [2+6+2]

2008
Distinguish between a semiconductor and a conductor. [2]
Mention what is a rectifier. With a neat circuit diagram, explain the working of a full wave
rectifier of junction diodes. Comment on its efficiency. [1+3+4+2]

2009
Describe the construction and working of a p-n-p transistor with necessary diagram and circuit.
Draw the common emitter input, output characteristics. Define input and output resistances.
[1+3+4+2]

2010
A pure semiconductor is obtained by doping germanium crystal with which of the following
elements? (a) silver (b) arsenic (c) gold (d) indium [1]
The emitter, collector and base of a transistor play almost the same role as played by the
filament, plate and ____________ in a vacuum triode. [1]
For a transistor,  = 0.96. Calculate  for it. [2]
Describe with neat circuit diagram, the working of junction diode as a full wave rectifier. Show
that for an ideal full-wave rectifier, the efficiency is 81.2 %. [2+6+2]

2011
A junction diode, when forward biased, behaves as device of ___________.
(a) no resistance (b) infinite resistance (c) high resistance (d) low resistance. [1]
If germanium has to be doped with an acceptor impurity, the region atom should be
(a) monovalent (b) divalent (c) trivalent (d) tetravalent [1]

2012
For a transistor (a) IE = IB + IC (b) IE = IB - IC (c) IE = IC - IB (d) IE = - IB – IC [1]

2013
Thermions carry (a) zero charge (b) positive charge
(c) negative charge (d) both positive and negative charge. [1]
Methods of connecting p-side of a junction diode to negative pole of the battery and the n-side
to the positive pole is called ____________ connection [1]
Draw the circuit diagram of a half wave rectifier made up of junction diode. [2]
According to band theory, compare a semiconductor with an insulator. [2]
An atom has energy bands like solids. (Write yes or no) [1]

2014
Name the charge carrier in p-type semiconductor. [1]
With a neat circuit diagram, explain the working of a full wave rectifier. Write the expression for
its efficiency. [2+4+1]

2015
The relationship between the transistor parameters  and  is
1+ β α α
(a) α =1+ β (b) α = (c) β= (d) β= [1]
β 1−α 1+α
Write the truth table for a two-input NAND gate [2]
Show the knee-voltage and breakdown voltage by drawing the characteristics curves for a
junction diode. [2]
With a neat circuit diagram, discuss the input and output characteristics of a transistor in CE
configuration. Define and explain the CM current amplification factor . [2 + 2+ 2+1]

2016
Write the truth table for two-input OR gate [1]
Write the truth table for three-input AND gate [2]
Compare between a conductor and a semiconductor discussing their energy bands. [2]
Discuss the nature of the output current and voltage in a full wave rectifier made of junction
diode. [2]

2017
In the given circuit diagram, a junction diode x ~ y has been connected to a source of emf. The
semiconductors x and y have been made by doping the germanium crystal with arsenic and
indium respectively. Then which of the following statements regarding the dipole is correct
(a) x is a p-type and y is n –type semiconductor and the diode is reverse biased.
(b) x is a n-type and y is p-type semiconductor and the diode is reverse biased.
(c) x is a p-type and y is n-type semiconductor and the diode is forward biased
(d) x is a n-type and y is p-type semiconductor and the diode is forward biased [1]
What is the ratio of the efficiency of a half wave rectifier to that of a full wave rectifier? [1]
Write the truth table and circuit symbol of a two input NAND gate. [2]
Explain the working of p-n-p transistor with a neat circuit diagram. Discuss its input and output
characteristic in CE configuration. [2+2+3]

2018
State the difference between p-type and n-type semiconductors. [2]
Write the circuit symbol and the truth table of a three input NOT gate. [3]
On the basis of band theory, distinguish among insulator, semiconductor and conductor of
electricity. [3]

2019
LED emits light when connected in ___________. (Forward bias, reverse bias) [1]
Write the circuit symbol and the truth table of a three input AND gate. [3]

2020
A p-type semiconductor
(a) is positively charged (b) is negatively charged
(c) has neutral charge (d) may be positively or negatively charged. [1]
Which logic gate is known as universal gate? [1]
Draw the circuit diagram of a p-n-p transistor in CE configuration. [1]
Draw the circuit symbol and write the truth table of a two-input NAND gate. [3]
What is a PN-junction diode? With a neat circuit diagram, describe the operation of a full wave
rectifier using junction diodes. [1+6]

2021
In a given circuit, the approximate value of voltage drop V0 across R is
(a) 10 V (b) 1 V (c) 0 V (d) 5 V [1]
The logic gate that operates on a single input only is
(a) OR (b) AND (c) NOT (d) NAND [1]
The most heavily doped region of a transistor is
(a) emitter (b) base (c) collector (d) base-collector junction. [1]
Draw the circuit symbol and write the truth table of a two input AND gate. [2]
With a neat circuit diagram explain the working of n-p-n transistor in CE configuration draw its
output characteristic. [7]

2022
The logic gate having only one input is (a) AND (b) OR (c) NOT (d) NOR [1]
The relation between transistor parameters and  is
α 1
(a) α =β (b) β= (c) β= (d) β=1+α [1]
1−α α
The number of diodes used in a half wave rectifier is (a) 1 (b) 2 (c) 3 (d) 4 [1]
Write the circuit symbol of and truth table for a NAND gate. [2]
Distinguish between p-type and n-type semiconductors. [2]
Draw the V-I characteristics for a PN-junction diode in forward bias and reverse bias condition.

2023
The relation between the transistor parameters  and  is
α β 1+α 1+ β
(a) β= (b) α = (c) β= (d) α = [1]
1−α β−1 α β
Which logic gate is known as the universal gate? [1]
What is a junction diode? Draw the circuit diagram for it in forward biased condition. [2]
Write the circuit symbol and truth table of a NOR gate. [2]
Describe the construction and characteristics of a Zener diode. Discuss its action as a voltage
regulator. [4+3]