1988
1. For a PN junction,
match the type of breakdown with phenomenon
i.
Avalanche breakdown
ii.
Zener breakdown
iii.
Punch through
a.
Collision of carriers
with crystal ions
b.
Early effect
c.
Rupture of covalent
bond due to strong electric field
Answer: i-a, ii-c, iii-b
1989
1. In a Zener diode,
a.
only P-region is
heavily doped
b.
only N-region is
heavily doped
c.
both P and N-regions
are heavily doped
d.
both P and N-regions
are lightly doped
Answer: C
1992
1. The 6 volts Zener
diode shown in figure has zero zener resistance and a knee current of 5 mA. The
minimum value of R so that the voltage across it does not fall below 6 volts is
……
Answer: B
Solution : https://www.youtube.com/watch?v=j45arOd6cYQ
1993
1. The wave shape of Vo
in the figure will be
1995
1. A Zener diode works
on the principle of
a.
Tunneling of charge
carriers across the junction
b.
Thermionic emission
c.
Diffusion of charge
carriers across the junction
d.
Hopping of charge
carriers across the junction
Answer: A
Solution : https://www.youtube.com/watch?v=4wq0h-QhMjk
1996
1. A Zener diode in the
circuit shown has a knee current of 5 mA, and a maximum allowed power
dissipation of 300 mW. What are the minimum and maximum load currents that can
be drawn safely from the circuit, keeping the output voltage Vo constant at 6
volts ?
a.
0 mA, 180 mA
b.
5 mA, 110 mA
c.
10 mA, 55 mA
d.
60 mA, 180 mA
Answer: C
Solution : https://www.youtube.com/watch?v=-OlZHuj8cPs
1999
1. A DC power supply has
a no-load voltage of 30 volts, and a full load voltage of 25 volts at a
full
load current of one amp. Its output resistance and load regulation,
respectively are
a.
5 Ω and 20 %
b.
25 Ω and 20 %
c.
5 Ω and 16.7 %
d.
25 Ω and 16.7 %
Answer: B
2001
1. The transistor shunt
regulator shown in figure has a regulated output voltage of 10 volts, when
input varies from 20 volts to 30 volts. The relevant parameters for the zener
diode and the transistor are: VZ = 9.5 volts, VBE = 0.3
votls, β = 99. Neglect the current throught RB.
Then the maximum power dissipated in the zener diode (PZ) and the
transistor (PT) are
Answer: C
2002
1. A zener diode regulator
in figure, is to be designed to meet the specifications : IL = 10
mA, Vo = 10 volts and Vin varies from 30 to 50 volts. The
zener diode has VZ = 10 volts and IZK (knee current) = 1
mA. For satisfactory operation
Answer: A
Solution : https://www.youtube.com/watch?v=OCR60jVExa4
2004
1. In the voltage regulator shown, the
load current can vary from 100 mA to 500 mA. Assuming that the zener diode is
ideal (i.e. the zener knee current is negligibly small and zener resistance is
zero in the breakdown region), the value of R is
Answer: D
Solution : https://www.youtube.com/watch?v=ow6gYqOD3_w
2005
1. The zener diode in
the regulator circuit shown has a zener voltage of 5.8 volts and a zener knee
current of 0.5 mA. The maximum load current drawn from this circuit ensuring
proper functioning over the input voltage range between 20 and 30 volts is
Answer: A
Solution : https://www.youtube.com/watch?v=QxmLyMhJs6g
2006
1. Find the correct
match between Group 1 and Group 2 :
Answer: C
Solution : https://www.youtube.com/watch?v=OkGp1dylZb4
2. For the circuit shown below, assume the
zener diode is ideal with a breakdown voltage of 6 volts. The waveform observed
across R is
Answer: B
Solution : https://www.youtube.com/watch?v=wjeTnzvlyrw
2007
1. Group I lists four
types of PN junction diodes. Match each device in Group I with one of the
option in Group II to indicate the bias condition of that device in its normal
mode of operation.
Answer: B
Solution : https://www.youtube.com/watch?v=4KUze2mrsoo
2. For the zener diode shown in the
figure, the zener voltage at knee is 7 volts, the knee current is negligible
and the zener dynamic resistance is 10 Ω. If the input
voltage (Vi) range is 10 to 16 volts, the output voltage (Vo)
ranges from
2008
1. In the following
limiter circuit, an input voltage Vi
= 10sin100πt applied. Assume that the diode drop
is 0.7 volts when it is forward biased. The zener breakdown voltage is 6.8
volts.
The maximum and
minimum values of the output voltage respectively are
a.
6.1 volts, -0.7 volts
b.
0.7 volts, -7.5 volts
c.
7.5 volts, -0.7 volts
d.
7.5 volts, -7.5 volts
Answer: C
Solution : https://www.youtube.com/watch?v=2LAYX1bdh5o
2. Consider the following assertions.
S1: For zener effect
to occur, a very abrupt junction is required
S2: For quantum
tunneling to occur, a very narrow energy barrier is required.
Which of the following
is correct?
a.
Only S2 is true
b.
Both are true but S2
is not a reason for S1
c.
Both are true but S2
is a reason for S1
d.
Both are false
Answer: A
Solution : https://www.youtube.com/watch?v=FMoJlAI1-84
2011
1. A Zener diode when
used in voltage stabilization circuits, is biased in
a.
Reverse bias region
below the breakdown voltage
b.
Reverse breakdown
region
c.
Forward bias region
d.
Forward bias constant
current mode
Answer: A
Solution : https://www.youtube.com/watch?v=FiBnG4KSEHU
2013
1. In the circuit shown
below, the knee current of ideal zener diode is 10 mA. To maintain 5 volts
across the load RL, the minimum value of RL in Ω’s and the minimum
power rating of the zener diode in mW respectively are
a.
125 and 125
b.
125 and 250
c.
250 and 125
d.
250 and 250
2015
1. In the circuit
shown below, the Zener diode is ideal and the Zener voltage is 6 volts. The
output voltage Vo (in volts) is _______________
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