Page 1
ELECTRONICS AND TELECOMMUNICATION
Time
Allowed
:
Three
Hours
Question Paper Specific Instructions
ENGINEERING
There are
EIGHT
questions divided in TWO sections.
Please read each of the
following instructions
carefully before
attempting
questions:
Candidate has to
attempt FIVE
questions in all.
Paper -I
Questions No. I and 5 are compulsory and out of the remaining, any THREE are to be
attempted choosing at least ONE
question from each
section.
The number of marks carried by a questionIpart is indicated against it.
Wherever any assumptions are made for answering a question, they must be clearly
indicated.
Diagrams/figures, wherever required, shall be drawn in the space provided for answering
the question itself.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Attempts of questions shall be counted in sequential order. Unless struck off, attempt of a
question shall be counted even if attempted partly.
Answers must be written in ENGLISH only.
Electron charge
Any page or portion of the page left blank in the Question-cum-Answer (QCA) Booklet must
be clearly struck off.
Values of constants which may be required:
Free space permeability
Free space permittivity
Maximum Marks : 300
Boltzmann constant
Velocity of light in free space
Planck's constant
|sGSE-OETE
SGSE-O-ETE
- I'6 x 1o19 Coulomb
4n X
10-
Henry/m
3 x 108 m/s
(1/36)x 10-9 Farad/m
1:38 x 1o28 J/K
6-626 x 1034J-s
UPSC ESE Mains Question Paper EC 23 June 2024
Page 2
ELECTRONICS AND TELECOMMUNICATION
Time
Allowed
:
Three
Hours
Question Paper Specific Instructions
ENGINEERING
There are
EIGHT
questions divided in TWO sections.
Please read each of the
following instructions
carefully before
attempting
questions:
Candidate has to
attempt FIVE
questions in all.
Paper -I
Questions No. I and 5 are compulsory and out of the remaining, any THREE are to be
attempted choosing at least ONE
question from each
section.
The number of marks carried by a questionIpart is indicated against it.
Wherever any assumptions are made for answering a question, they must be clearly
indicated.
Diagrams/figures, wherever required, shall be drawn in the space provided for answering
the question itself.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Attempts of questions shall be counted in sequential order. Unless struck off, attempt of a
question shall be counted even if attempted partly.
Answers must be written in ENGLISH only.
Electron charge
Any page or portion of the page left blank in the Question-cum-Answer (QCA) Booklet must
be clearly struck off.
Values of constants which may be required:
Free space permeability
Free space permittivity
Maximum Marks : 300
Boltzmann constant
Velocity of light in free space
Planck's constant
|sGSE-OETE
SGSE-O-ETE
- I'6 x 1o19 Coulomb
4n X
10-
Henry/m
3 x 108 m/s
(1/36)x 10-9 Farad/m
1:38 x 1o28 J/K
6-626 x 1034J-s
UPSC ESE Mains Question Paper EC 23 June 2024
QI. (a)
(b)
(c)
(d)
Consider an ideal pMOS capacitor of area 100 um x 100 um operated
at T = 300 K. èM (work function for the metal) = 52 eV,
X, (oxide
thickness) = 3 nm and Nn = 101/em.
Calculate the flat
Assume
band voltage VFB and
the threshold voltage VTp.
Eor = 3:43 x 10-18 Flem, V (thermal voltage)
= 0-026 V, n; = 100/cm®
Zs;
(electron affinity of Si) = 4-05 eV, Eg = 112 eV and Esi = 10-12
Flcm. 19
In the circuit shown in the figure below, M, serves as an electronic
switch. If v, is very small, determine W/L such that circuit attenuates
the signal by 5%.
Assume Vc = 18V and R, = 100 2.
Hn
Cor
200
4A
Source.
Vin
SECTION A
250 V +
SGSE-O-ETE
and VTN = 0:4 V.
VG
M
Find the voltage v, in the circuit shown in the figure using source
transformation. Also, find the power developed by the 250 V voltage
25 S2
oVout
W
)8A
22
Vo 100Q
52
An electrical load absorbs an average power of 85 kW at lagging power
factor of 0-85. If the load operates at 240 V rms, calculate the complex
power and
impedance of the load.
12
12
¿ 15 2
12
Page 3
ELECTRONICS AND TELECOMMUNICATION
Time
Allowed
:
Three
Hours
Question Paper Specific Instructions
ENGINEERING
There are
EIGHT
questions divided in TWO sections.
Please read each of the
following instructions
carefully before
attempting
questions:
Candidate has to
attempt FIVE
questions in all.
Paper -I
Questions No. I and 5 are compulsory and out of the remaining, any THREE are to be
attempted choosing at least ONE
question from each
section.
The number of marks carried by a questionIpart is indicated against it.
Wherever any assumptions are made for answering a question, they must be clearly
indicated.
Diagrams/figures, wherever required, shall be drawn in the space provided for answering
the question itself.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Attempts of questions shall be counted in sequential order. Unless struck off, attempt of a
question shall be counted even if attempted partly.
Answers must be written in ENGLISH only.
Electron charge
Any page or portion of the page left blank in the Question-cum-Answer (QCA) Booklet must
be clearly struck off.
Values of constants which may be required:
Free space permeability
Free space permittivity
Maximum Marks : 300
Boltzmann constant
Velocity of light in free space
Planck's constant
|sGSE-OETE
SGSE-O-ETE
- I'6 x 1o19 Coulomb
4n X
10-
Henry/m
3 x 108 m/s
(1/36)x 10-9 Farad/m
1:38 x 1o28 J/K
6-626 x 1034J-s
UPSC ESE Mains Question Paper EC 23 June 2024
QI. (a)
(b)
(c)
(d)
Consider an ideal pMOS capacitor of area 100 um x 100 um operated
at T = 300 K. èM (work function for the metal) = 52 eV,
X, (oxide
thickness) = 3 nm and Nn = 101/em.
Calculate the flat
Assume
band voltage VFB and
the threshold voltage VTp.
Eor = 3:43 x 10-18 Flem, V (thermal voltage)
= 0-026 V, n; = 100/cm®
Zs;
(electron affinity of Si) = 4-05 eV, Eg = 112 eV and Esi = 10-12
Flcm. 19
In the circuit shown in the figure below, M, serves as an electronic
switch. If v, is very small, determine W/L such that circuit attenuates
the signal by 5%.
Assume Vc = 18V and R, = 100 2.
Hn
Cor
200
4A
Source.
Vin
SECTION A
250 V +
SGSE-O-ETE
and VTN = 0:4 V.
VG
M
Find the voltage v, in the circuit shown in the figure using source
transformation. Also, find the power developed by the 250 V voltage
25 S2
oVout
W
)8A
22
Vo 100Q
52
An electrical load absorbs an average power of 85 kW at lagging power
factor of 0-85. If the load operates at 240 V rms, calculate the complex
power and
impedance of the load.
12
12
¿ 15 2
12
Draw
neat
sketches
of
the
edge
and
screw
dislocations.
IIlustrate
the
Burger's
vector
on
the
sketches
of
(1)
6
(e)
Calculate
the
line
energy
of
dislocation
in
BCC
iron
if
the
shear
modulus
and
lattice
parameter
of
BCC
iron
are
80-2
GN/m
and
2-87 Å, respectively.
(ii)
A p-n junction
Q2. (a)
N
=3x
1018
/em,
Np
=
2x
1016/cm3
D,
=
25
cm²/s,
D,
=
10
cm/s
Tn0
=
4
x
10-
s,
Tno
=
10-
s
20
The
photocurrent
density
J,
=
20
mA/cm².
Calculate
the
open
circuit
voltage
of
the
solar
cell
at
T
=
300
K.
Assume
n;
=
1:5
x
1010/cm3.
5
though the armature
What
are
the
two
functions
of
commutator
in
DC
machines
?
Explain
how
the
commutator
keeps
the
armature
mmf
stationary
in
space,
along
the
interpolar
axis,
even
(i)
(b)
(ii)
15
rotates.
10
Explain why
(i)
(c)
10
Differentiate
between
different
types
of
magnetic
(ii)
Design a
Widlar
(i)
(a)
10
Q3.
R$
V BE2
VBE1
10
Design
an
amplifier
that
has
a
voltage
gain
of
2
if
VÊN
<0
and
1,
if
VIN
>
0.
Assume
ideal
diodes
and
ideal
op
amps
are
availabie.
(ii)
3
SGSE-O-ETE
dislocations.
solar
cell
is
fabricated
using
silicon
and
has
the
following
important parameters
end-centred
tetragonal
geometry
does
not
exist
in
Bravais crystal structures.
materials on the
basis
of
magnetic
dipoles
and
hysteresis
loops.
current
source
shown in the
figure
below
to
give
I,
=
5
A
and
IR
=
1
m¢.
The
parameters
are
Voc
=
30
V,
VBE1
=
07
V,
V
=
26
mV
and
Bp
=
100.
Page 4
ELECTRONICS AND TELECOMMUNICATION
Time
Allowed
:
Three
Hours
Question Paper Specific Instructions
ENGINEERING
There are
EIGHT
questions divided in TWO sections.
Please read each of the
following instructions
carefully before
attempting
questions:
Candidate has to
attempt FIVE
questions in all.
Paper -I
Questions No. I and 5 are compulsory and out of the remaining, any THREE are to be
attempted choosing at least ONE
question from each
section.
The number of marks carried by a questionIpart is indicated against it.
Wherever any assumptions are made for answering a question, they must be clearly
indicated.
Diagrams/figures, wherever required, shall be drawn in the space provided for answering
the question itself.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Attempts of questions shall be counted in sequential order. Unless struck off, attempt of a
question shall be counted even if attempted partly.
Answers must be written in ENGLISH only.
Electron charge
Any page or portion of the page left blank in the Question-cum-Answer (QCA) Booklet must
be clearly struck off.
Values of constants which may be required:
Free space permeability
Free space permittivity
Maximum Marks : 300
Boltzmann constant
Velocity of light in free space
Planck's constant
|sGSE-OETE
SGSE-O-ETE
- I'6 x 1o19 Coulomb
4n X
10-
Henry/m
3 x 108 m/s
(1/36)x 10-9 Farad/m
1:38 x 1o28 J/K
6-626 x 1034J-s
UPSC ESE Mains Question Paper EC 23 June 2024
QI. (a)
(b)
(c)
(d)
Consider an ideal pMOS capacitor of area 100 um x 100 um operated
at T = 300 K. èM (work function for the metal) = 52 eV,
X, (oxide
thickness) = 3 nm and Nn = 101/em.
Calculate the flat
Assume
band voltage VFB and
the threshold voltage VTp.
Eor = 3:43 x 10-18 Flem, V (thermal voltage)
= 0-026 V, n; = 100/cm®
Zs;
(electron affinity of Si) = 4-05 eV, Eg = 112 eV and Esi = 10-12
Flcm. 19
In the circuit shown in the figure below, M, serves as an electronic
switch. If v, is very small, determine W/L such that circuit attenuates
the signal by 5%.
Assume Vc = 18V and R, = 100 2.
Hn
Cor
200
4A
Source.
Vin
SECTION A
250 V +
SGSE-O-ETE
and VTN = 0:4 V.
VG
M
Find the voltage v, in the circuit shown in the figure using source
transformation. Also, find the power developed by the 250 V voltage
25 S2
oVout
W
)8A
22
Vo 100Q
52
An electrical load absorbs an average power of 85 kW at lagging power
factor of 0-85. If the load operates at 240 V rms, calculate the complex
power and
impedance of the load.
12
12
¿ 15 2
12
Draw
neat
sketches
of
the
edge
and
screw
dislocations.
IIlustrate
the
Burger's
vector
on
the
sketches
of
(1)
6
(e)
Calculate
the
line
energy
of
dislocation
in
BCC
iron
if
the
shear
modulus
and
lattice
parameter
of
BCC
iron
are
80-2
GN/m
and
2-87 Å, respectively.
(ii)
A p-n junction
Q2. (a)
N
=3x
1018
/em,
Np
=
2x
1016/cm3
D,
=
25
cm²/s,
D,
=
10
cm/s
Tn0
=
4
x
10-
s,
Tno
=
10-
s
20
The
photocurrent
density
J,
=
20
mA/cm².
Calculate
the
open
circuit
voltage
of
the
solar
cell
at
T
=
300
K.
Assume
n;
=
1:5
x
1010/cm3.
5
though the armature
What
are
the
two
functions
of
commutator
in
DC
machines
?
Explain
how
the
commutator
keeps
the
armature
mmf
stationary
in
space,
along
the
interpolar
axis,
even
(i)
(b)
(ii)
15
rotates.
10
Explain why
(i)
(c)
10
Differentiate
between
different
types
of
magnetic
(ii)
Design a
Widlar
(i)
(a)
10
Q3.
R$
V BE2
VBE1
10
Design
an
amplifier
that
has
a
voltage
gain
of
2
if
VÊN
<0
and
1,
if
VIN
>
0.
Assume
ideal
diodes
and
ideal
op
amps
are
availabie.
(ii)
3
SGSE-O-ETE
dislocations.
solar
cell
is
fabricated
using
silicon
and
has
the
following
important parameters
end-centred
tetragonal
geometry
does
not
exist
in
Bravais crystal structures.
materials on the
basis
of
magnetic
dipoles
and
hysteresis
loops.
current
source
shown in the
figure
below
to
give
I,
=
5
A
and
IR
=
1
m¢.
The
parameters
are
Voc
=
30
V,
VBE1
=
07
V,
V
=
26
mV
and
Bp
=
100.
(b)
(c)
Q4. (a)
()
(ii)
(i)
(ii)
Discuss the points of similarities between a transformer and
induction machine. Explain, why an induction machine is called a
generalized transformer.
sGSEoETE|
A 10 kVA/2500/250 V, single-phase transformer has the following
parameters :
Primary winding (h.v. side): Resistance rË = 24 2
Leakage
Reactance, x1 = 6-00 2
Secondary winding (l.v. side): Resistance r = 0-03 S2
Leakage
Reactance, X, = 0:07 2
With primary supply voltage held constant at 2500 V, calculate
the secondary terminal voltage, when the low voltage winding is
connected to a load impedance of 5 +j 35 2 and the transformer
delivers its rated current at 08 p.f. lagging on the low voltage
side.
Discuss photoelectric efiect and find out the number of
photoelectrons emitted per unit time from a transmitter operated
at a frequency of 800 kHz and 10 kW power.
Define dielectric strength. Discuss different types of dielectric
breakdowns in solids.
1 k2
HE
For the circuit shown in the figure below, determine the frequency of
oscillation f, and overall voltage gain Ay. Also identify the type of
Oscillator. (Assume op amps are ideal) 20
A
W
1 kQ
4
1 k2
W
10
1 uF
10
10
10
Page 5
ELECTRONICS AND TELECOMMUNICATION
Time
Allowed
:
Three
Hours
Question Paper Specific Instructions
ENGINEERING
There are
EIGHT
questions divided in TWO sections.
Please read each of the
following instructions
carefully before
attempting
questions:
Candidate has to
attempt FIVE
questions in all.
Paper -I
Questions No. I and 5 are compulsory and out of the remaining, any THREE are to be
attempted choosing at least ONE
question from each
section.
The number of marks carried by a questionIpart is indicated against it.
Wherever any assumptions are made for answering a question, they must be clearly
indicated.
Diagrams/figures, wherever required, shall be drawn in the space provided for answering
the question itself.
Unless otherwise mentioned, symbols and notations have their usual standard meanings.
Attempts of questions shall be counted in sequential order. Unless struck off, attempt of a
question shall be counted even if attempted partly.
Answers must be written in ENGLISH only.
Electron charge
Any page or portion of the page left blank in the Question-cum-Answer (QCA) Booklet must
be clearly struck off.
Values of constants which may be required:
Free space permeability
Free space permittivity
Maximum Marks : 300
Boltzmann constant
Velocity of light in free space
Planck's constant
|sGSE-OETE
SGSE-O-ETE
- I'6 x 1o19 Coulomb
4n X
10-
Henry/m
3 x 108 m/s
(1/36)x 10-9 Farad/m
1:38 x 1o28 J/K
6-626 x 1034J-s
UPSC ESE Mains Question Paper EC 23 June 2024
QI. (a)
(b)
(c)
(d)
Consider an ideal pMOS capacitor of area 100 um x 100 um operated
at T = 300 K. èM (work function for the metal) = 52 eV,
X, (oxide
thickness) = 3 nm and Nn = 101/em.
Calculate the flat
Assume
band voltage VFB and
the threshold voltage VTp.
Eor = 3:43 x 10-18 Flem, V (thermal voltage)
= 0-026 V, n; = 100/cm®
Zs;
(electron affinity of Si) = 4-05 eV, Eg = 112 eV and Esi = 10-12
Flcm. 19
In the circuit shown in the figure below, M, serves as an electronic
switch. If v, is very small, determine W/L such that circuit attenuates
the signal by 5%.
Assume Vc = 18V and R, = 100 2.
Hn
Cor
200
4A
Source.
Vin
SECTION A
250 V +
SGSE-O-ETE
and VTN = 0:4 V.
VG
M
Find the voltage v, in the circuit shown in the figure using source
transformation. Also, find the power developed by the 250 V voltage
25 S2
oVout
W
)8A
22
Vo 100Q
52
An electrical load absorbs an average power of 85 kW at lagging power
factor of 0-85. If the load operates at 240 V rms, calculate the complex
power and
impedance of the load.
12
12
¿ 15 2
12
Draw
neat
sketches
of
the
edge
and
screw
dislocations.
IIlustrate
the
Burger's
vector
on
the
sketches
of
(1)
6
(e)
Calculate
the
line
energy
of
dislocation
in
BCC
iron
if
the
shear
modulus
and
lattice
parameter
of
BCC
iron
are
80-2
GN/m
and
2-87 Å, respectively.
(ii)
A p-n junction
Q2. (a)
N
=3x
1018
/em,
Np
=
2x
1016/cm3
D,
=
25
cm²/s,
D,
=
10
cm/s
Tn0
=
4
x
10-
s,
Tno
=
10-
s
20
The
photocurrent
density
J,
=
20
mA/cm².
Calculate
the
open
circuit
voltage
of
the
solar
cell
at
T
=
300
K.
Assume
n;
=
1:5
x
1010/cm3.
5
though the armature
What
are
the
two
functions
of
commutator
in
DC
machines
?
Explain
how
the
commutator
keeps
the
armature
mmf
stationary
in
space,
along
the
interpolar
axis,
even
(i)
(b)
(ii)
15
rotates.
10
Explain why
(i)
(c)
10
Differentiate
between
different
types
of
magnetic
(ii)
Design a
Widlar
(i)
(a)
10
Q3.
R$
V BE2
VBE1
10
Design
an
amplifier
that
has
a
voltage
gain
of
2
if
VÊN
<0
and
1,
if
VIN
>
0.
Assume
ideal
diodes
and
ideal
op
amps
are
availabie.
(ii)
3
SGSE-O-ETE
dislocations.
solar
cell
is
fabricated
using
silicon
and
has
the
following
important parameters
end-centred
tetragonal
geometry
does
not
exist
in
Bravais crystal structures.
materials on the
basis
of
magnetic
dipoles
and
hysteresis
loops.
current
source
shown in the
figure
below
to
give
I,
=
5
A
and
IR
=
1
m¢.
The
parameters
are
Voc
=
30
V,
VBE1
=
07
V,
V
=
26
mV
and
Bp
=
100.
(b)
(c)
Q4. (a)
()
(ii)
(i)
(ii)
Discuss the points of similarities between a transformer and
induction machine. Explain, why an induction machine is called a
generalized transformer.
sGSEoETE|
A 10 kVA/2500/250 V, single-phase transformer has the following
parameters :
Primary winding (h.v. side): Resistance rË = 24 2
Leakage
Reactance, x1 = 6-00 2
Secondary winding (l.v. side): Resistance r = 0-03 S2
Leakage
Reactance, X, = 0:07 2
With primary supply voltage held constant at 2500 V, calculate
the secondary terminal voltage, when the low voltage winding is
connected to a load impedance of 5 +j 35 2 and the transformer
delivers its rated current at 08 p.f. lagging on the low voltage
side.
Discuss photoelectric efiect and find out the number of
photoelectrons emitted per unit time from a transmitter operated
at a frequency of 800 kHz and 10 kW power.
Define dielectric strength. Discuss different types of dielectric
breakdowns in solids.
1 k2
HE
For the circuit shown in the figure below, determine the frequency of
oscillation f, and overall voltage gain Ay. Also identify the type of
Oscillator. (Assume op amps are ideal) 20
A
W
1 kQ
4
1 k2
W
10
1 uF
10
10
10
(b)
(c)
(i)
Determine the
impedance Z,,
that results in
maximum average
power
transferred to Z,. for the
circuit shown in the
figure.
Calculate the maximum average power transferred to the oad
impedance determined.
20/0°,V
5Q
SGSE-O-ETE
Given : erf (0-95) = 0-8209
(ii) What are the major factors that have led to the acceleration and
development of solar and wind power ?
erf (1·0) = 0-8427
To produce a p-type semiconductor, the boron is doped in pure
silicon. Doping is done through a B,03 vapour phase of a surface
concentration equivalent to 3-3 x 1028 boron atoms/m². Calculate the
time required to get a boron content of 1028 atoms/m at a depth
of 2 um. The doping temperature is 1000°C and Dg in Si at this
temperature is 4 x 10-17 mn/s.
erf (2-4)= 0-9993
W
erf (2-6)= 09998
202
5
j3 2
000
a
10
10
20
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