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Recent questions and answers in Electromagnetics
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1
GATE2020EC: 13
The impedances $Z=jX,$ for all $X$ in the range $\left ( \infty ,\infty \right )$, map to the Smith chart as a circle of radius $1$ with centre at $(0, 0)$. a point at the centre of the chart. a line passing through the centre of the chart. a circle of radius $0.5$ with centre at $(0.5, 0)$.
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Feb 13
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Electromagnetics
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jothee
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gate2020ec
impedance
electromagnetics
0
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0
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2
GATE2020EC: 21
A transmission line of length $3\lambda /4$ and having a characteristic impedance of $50$ $\Omega$ is terminated with a load of $400 \Omega$. The impedance (rounded off to two decimal places) seen at the input end of the transmission line is __________ $\Omega$.
asked
Feb 13
in
Electromagnetics
by
jothee
(
1.4k
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gate2020ec
numericalanswers
impedance
electromagnetics
0
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0
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3
GATE2020EC: 43
For an infinitesimally small dipole in free space, the electric field $E_{\theta }$ in the far field is proportional to $e^{jkr/r}\sin\theta$, where $k=2\pi /\lambda$. A vertical infinitesimally small electric dipole $\left (\delta l \ll \lambda \right )$ is placed ... far field radiation pattern occurs at $\theta =60^{\circ}$, is $\lambda$ $0.5\lambda$ $0.25\lambda$ $0.75\lambda$
asked
Feb 13
in
Electromagnetics
by
jothee
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1.4k
points)
gate2020ec
electromagnetics
radiationpattern
0
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0
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4
GATE2020EC: 45
The magnetic field of a uniform plane wave in vacuum is given by $\overrightarrow{H}\left ( x,y,z,t \right )=(\hat{a_{x}}+2\hat{a_{y}}+b\hat{a_{z}})\cos\left ( \omega t+3xyz\right ).$ The value of $b$ is ___________.
asked
Feb 13
in
Electromagnetics
by
jothee
(
1.4k
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gate2020ec
numericalanswers
planewavesandproperties
electromagnetics
0
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0
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5
GATE2020EC: 46
For a $2$port network consisting of an ideal lossless transformer, the parameter $S_{21}$ (rounded off to two decimal places) for a reference impedance of $10 \Omega$, is __________.
asked
Feb 13
in
Electromagnetics
by
jothee
(
1.4k
points)
gate2020ec
numericalanswers
impedance
electromagnetics
0
votes
0
answers
6
GATE2019 EC: 12
In the table shown, List I and List II, respectively, contain terms appearing on the lefthand side and the righthand side of Maxwell's equations (in their standard form). Match the lefthand side with the corresponding righthand side. ... $1Q,2R,3P,4S$ $1Q,2S,3P,4R$ $1R,2Q,3S,4P$
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Feb 12, 2019
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Electromagnetics
by
Arjun
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1.4k
points)
gate2019ec
electromagnetics
maxwell'sequations
0
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0
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7
GATE2019 EC: 23
Radiation resistance of a small dipole current element of length $l$ at a frequency of $3$ GHz is $3$ ohms. If the length is changed by $1\%$, then the percentage change in the radiation resistance, rounded off to two decimal places, is ________ $\%.$
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Feb 12, 2019
in
Electromagnetics
by
Arjun
(
1.4k
points)
gate2019ec
numericalanswers
electromagnetics
radiationpattern
0
votes
0
answers
8
GATE2019 EC: 24
In the circuit shown, $V_{s}$ is square wave of period $T$ with maximum and minimum values of $8\: V$ and $10\: V$, respectively. Assume that the diode is ideal and $R_{1}=R_{2}=50\: \Omega.$ The average value of $V_{L}$ is _______ volts (rounded off to $1$ decimal place).
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Feb 12, 2019
in
Electromagnetics
by
Arjun
(
1.4k
points)
gate2019ec
numericalanswers
electromagnetics
waveequation
0
votes
0
answers
9
GATE2019 EC: 37
The dispersion equation of a waveguide, which relates the wavenumber $k$ to the frequency $\omega$ is $k(\omega)= (1/c) \sqrt{\omega^{2}\omega_{\circ}^{2}}$ where the speed of light $c= 2 \times 10^{8}\: m/s$ and $\omega_{\circ}$ ... $2 \times 10^{8}\: m/s$ $3 \times 10^{8}\: m/s$ $4.5 \times 10^{8}\: m/s$
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Feb 12, 2019
in
Electromagnetics
by
Arjun
(
1.4k
points)
gate2019ec
electromagnetics
waveguides
0
votes
0
answers
10
GATE2019 EC: 51
A rectangular waveguide of width $w$ and height $h$ has cutoff frequencies for $TE_{10}$ and $TE_{11}$ modes in the ration $1:2$ . The aspect ratio $w/h$, rounded off to two decimal places , is _______.
asked
Feb 12, 2019
in
Electromagnetics
by
Arjun
(
1.4k
points)
gate2019ec
numericalanswers
electromagnetics
waveguides
0
votes
0
answers
11
GATE2016324
If a righthanded circularly polarized wave is incident normally on a plane perfect conductor, then the reflected wave will be righthanded circularly polarized lefthanded circularly polarized elliptically polarized with a tilt angle of $45^ \circ$ horizontally polarized
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Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
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gate2016ec3
electromagnetics
polarization
0
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0
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12
GATE2016325
Faraday's law of electromagnetic induction is mathematically described by which one of the following equations? $\nabla\ \bullet \overrightarrow{B} = 0$ $\nabla\ \bullet \overrightarrow{D} = \rho_V$ ...
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec3
electromagnetics
0
votes
0
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13
GATE2016352
Consider an airfilled rectangular waveguide with dimensions $a=2.286\:cm$ and $b=1.016\:cm$. At $10 \:GHz$ operating frequency, the value of the propagation constant (per meter) of the corresponding propagation mode is _______
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec3
numericalanswers
electromagnetics
waveguides
0
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0
answers
14
GATE2016353
Consider an airfilled rectangular waveguide with dimensions $a=2.286\:cm$ and $b=1.016\:cm$. The increasing order of the cutoff frequencies for different modes is $TE_{01}<TE_{10}<TE_{11}<TE_{20}$ $TE_{20}<TE_{11}<TE_{10}<TE_{01}$ $TE_{10}<TE_{20}<TE_{01}<TE_{11}$ $TE_{10}<TE_{11}<TE_{20}<TE_{01}$
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec3
electromagnetics
waveguides
0
votes
0
answers
15
GATE2016354
A radar operating at $5\:GHz$ uses a common antenna for transmission and reception. The antenna has a gain of $150$ and is aligned for maximum directional radiation and reception to a target $1\:km$ away having radar crosssection of $3\:m^2$. If it transmits $100\:kW$, then the received power (in $\mu W)$ is _______
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec3
numericalanswers
electromagnetics
antennas
0
votes
0
answers
16
GATE2016355
Consider the charge profile shown in the figure. The resultant potential distribution is best described by
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Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
points)
gate2016ec3
electromagnetics
0
votes
0
answers
17
GATE2016223
A uniform and constant magnetic field $\textbf{B}=\hat{z}B$ exists in the $\hat{z}$ direction in vacuum. A particle of mass $m$ with a small charge $q$ is introduced into this region with an initial velocity $\textbf{v}=\hat{x}v_{x}+\hat{z}v_{z}$. ... $xy$ plane. Linear motion in the $\hat{z}$ direction. Linear motion in the $\hat{x}$ direction.
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec2
electromagnetics
0
votes
0
answers
18
GATE2016224
Let the electric field vector of a plane electromagnetic wave propagating in a homogeneous medium be expressed as $\textbf{E}=\hat{x}E_{x}e^{j(\omega t\beta z)},$ where the propogation constant $\beta$ is a function of the angular frequency $\omega$. ... polarization of the wave. The group velocity of the wave. The phase velocity of the wave. The power flux through the $z=0$ plane.
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec2
electromagnetics
0
votes
0
answers
19
GATE2016225
Light from free space is incident at an angle $\theta _{i}$ to the normal of the facet of a stepindex large core optical fibre. The core and cladding refractive indices are $n _{1}=1.5$ and $n _{2}=1.4$, respectively. The maximum value of $\theta _{i}$ (in degrees) for which the incident light will be guided in the core of the fibre is _________
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec2
numericalanswers
electromagnetics
opticalfiber
0
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0
answers
20
GATE2016253
A lossless microstrip transmission line consists of a trace of width $w$. It is drawn over a pratically infinite ground plane and is separated by a dielectric slab of thickness $t$ and relative permittivity $\varepsilon _{r}> 1.$ The inductance per unit length and the characteristic ... $Z_{0}< \sqrt{\frac{Lt}{\varepsilon _{0}\varepsilon _{\gamma}t}}$
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec2
electromagnetics
0
votes
0
answers
21
GATE2016254
A microwave circuit consisting of lossless transmission lines $T_{1}$ and $T_{2}$ is shown in the figure. The plot shows the magnitude of the input reflection coefficient $\Gamma$ as a function of frequency $f$. The phase velocity of the signal in the transmission lines is $2\times 10^{8}$ $m/s$. The length $L$ (in meters) of $T_{2}$ is _________
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec2
numericalanswers
electromagnetics
transmissionlines
0
votes
0
answers
22
GATE2016125
The propagation constant of a lossy transmission line is $(2+j5) m^{1}$ and its characteristic impedance is $(50+j0) \Omega$ at $\omega = 10^6 rad \: s^{1}$ ... $L = 250 \: \mu H/m, C = 0.2 \: \mu F/m, R=50 \: \Omega /m, \: G=0.04 \: S/m$
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec1
impedance
electromagnetics
0
votes
0
answers
23
GATE2016152
An antenna pointing in a certain direction has a noise temperature of $50 \: K$. The ambient temperature is $290 \: K$. The antenna is connected to a preamplifier that has a noise figure of $2$ dB and an available gain of $40$ dB over an effective bandwidth of $12$ MHz. The effective ... $P_{a0} = 3.85 \times 10^{10}W$ $T_e = 160.62\thinspace K$ and $P_{a0} = 4.6\times 10^{10}W$
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec1
electromagnetics
antennas
0
votes
0
answers
24
GATE2016153
Two lossless Xband horn antennas are separated by a distance of $200 \lambda$. The amplitude reflection coefficients at the terminals of the transmitting and receiving antennas are $0.15$ and $0.18$,respectively. The maximum directives of the ... antennas are perfectly aligned and polarization matched, the power ( in mW) delivered to the load at the receiver is _________
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec1
numericalanswers
electromagnetics
antennas
0
votes
0
answers
25
GATE2016154
The electric field of a uniform plane wave traveling along the negative $z$ direction is given by the following equation: ${\overrightarrow {E}^i_w= ( \hat {a}_x+ j\hat {a}_y)E_0e^{jkz}}$ This wave is incident upon a receiving antenna placed at the origin and ... ), $5$dB Circular(clockwise), Linear, $5$dB Circular(clockwise), Linear, $3$dB Circular(anti clockwise), Linear, $3$dB
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec1
planewavesandproperties
electromagnetics
0
votes
0
answers
26
GATE2016155
The farzone power density radiated by a helical antenna is approximated as: ${\overrightarrow W_{rad}= \overrightarrow W_{average} \approx \hat {a_r}C_0\frac{1}{r^2}\cos^4\theta}$ The radiated power density is symmetrical with respect to $\phi$ and exists only ... and the maximum directivity of the antenna, respectively, are $1.5C_0,10dB$ $1.256C_0,10dB$ $1.256C_0,12dB$ $1.5C_0,12dB$
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2016ec1
electromagnetics
antennas
0
votes
0
answers
27
GATE2015324
The directivity of an antenna array can be increased by adding more antenna elements, as a larger number of elements improves the radiation efficiency increases the effective area of the antenna results in a better impedance matching allows more power to be transmitted by the antenna
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
points)
gate2015ec3
electromagnetics
antennas
0
votes
0
answers
28
GATE2015325
A coaxial cable is made of two brass conductors. The spacing between the conductors is filled with Teflon $(\varepsilon_{r} = 2.1, \tan \delta = 0).$ Which one of the following circuits can represent the lumped element model of a small piece of this cable having length $\Delta z$?
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
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gate2015ec3
electromagnetics
0
votes
0
answers
29
GATE2015353
Consider the $3\:m$ long lossless airfilled transmission line shown in the figure. It has a characteristic impedance of $120\pi\: \Omega,$ is terminated by a short circuit, and is excited with a frequency of $37.5\: MHz.$ What is the nature of the input impedance $(Z_{in})?$ Open Short Inductive Capacitive
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
points)
gate2015ec3
electromagnetics
impedance
0
votes
0
answers
30
GATE2015224
In a source free region in vacuum, if the electrostatic potential $\varphi = 2x^{2} + y^{2} + cz^{2},$ the value of constant ܿ$c$ must be _______.
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2015ec2
numericalanswers
electromagnetics
0
votes
0
answers
31
GATE2015225
The electric field of a uniform plane electromagnetic wave is $\overrightarrow{E} = \left(\overrightarrow{a}_{x} + j 4 \overrightarrow{a}_{y}\right) \text{exp }[j(2\pi \times 10^{7}t – 0.2z)].$ The polarization of the wave is right handed circular right handed elliptical left handed circular left handed elliptical
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2015ec2
electromagnetics
0
votes
0
answers
32
GATE2015253
An airfilled rectangular waveguide of internal dimensions $a\: cm \times b\: cm\:(a>b)$ has a cutoff frequency of $6\:GHz$ for the dominant $TE_{10}$ mode. For the same waveguide, if the cutoff frequency of the $TM_{11}$mode is $15\: GHz,$ the cutoff frequency of the $TE_{01}$ mode in $GHz$ is __________.
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Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
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gate2015ec2
numericalanswers
electromagnetics
waveguides
0
votes
0
answers
33
GATE2015255
The electric field of a plane wave propagating in a lossless nonmagnetic medium is given by the following expression $\text{E}(z,t) = \textbf{a}_{x} 5 \cos(2\pi \times 10^{9}t + \beta z) + \textbf{a}_{y} 3 \cos\left(2\pi \times 10^{9} t + \beta z – \frac{\pi}{2}\right)$ The type of the polarization is Right Hand Circular Left Hand Elliptical Right Hand Elliptical Linear
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
points)
gate2015ec2
electromagnetics
propagation
0
votes
0
answers
34
GATE2015121
The polar plot of the transfer function $G(s) = \frac{10(s+1)}{s+10}$ for $0 \leq \omega < \infty$ will be in the first quadrant second quadrant third quadrant fourth quadrant
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Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2015ec1
electromagnetics
polarization
0
votes
0
answers
35
GATE2015125
The electric field component of a plane wave traveling in a lossless dielectric medium is given by $\overrightarrow{E}(z,t) = \hat{a}_y 2 \cos \bigg( 10^st\frac{z}{\sqrt{2}} \bigg) \: V/m$. The wavelength (in m) for the wave is ___________.
asked
Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
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gate2015ec1
numericalanswers
planewavesandproperties
electromagnetics
0
votes
0
answers
36
GATE2015137
All the logic gates shown in the figure have a propagation delay of $20$ ns. Let $A=C=0$ and $B=1$ until time $t=0$. At $t=0$, all the inputs flip (i.e., $A=C=1$ and $B=0$) and remain in that state. For $t>0$, output $Z=1$ for a duration (in ns) of ________.
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Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
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gate2015ec1
numericalanswers
electromagnetics
propagation
0
votes
0
answers
37
GATE2015153
The longitudinal component of the magnetic field inside an airfilled rectangular waveguide made of a perfect electric conductor is given by the following expression ... $b=0.033 \: m$. The mode of propagation inside the waveguide is $TM_{12}$ $TM_{21}$ $TE_{21}$ $TE_{12}$
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Mar 28, 2018
in
Electromagnetics
by
Milicevic3306
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gate2015ec1
electromagnetics
propagation
0
votes
0
answers
38
GATE201448
At $T=300 \:K$, the band gap and the intrinsic carrier concentration of GaAs are $1.42$ eV and $10^6 \: cm^{3}$, respectively. In order to generate electron hole pairs in GaAs, which one of the wavelength $(\lambda_C)$ ranges of incident radiation, is most suitable? (Given that: Plank's ... $1.62 \: \mu m < \lambda _C < 6.62 \: \mu m$
asked
Mar 26, 2018
in
Electromagnetics
by
Milicevic3306
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15.8k
points)
gate2014ec4
electromagnetics
plank'sconstant
0
votes
0
answers
39
GATE2014411
If the emitter resistance in a commonemitter voltage amplifier is not bypassed, it will reduce both the voltage gain and the input impedance reduce the voltage gain and increase the input impedance increase the voltage gain and reduce the input impedance reduce both the voltage gain and the input impedance
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Mar 26, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
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gate2014ec4
electromagnetics
impedance
0
votes
0
answers
40
GATE2014424
For an antenna radiating in free space, the electric field at a distance of $1$ km is found to be $12 \: mV/m$. Given that intrinsic impedance of the free space is $120 \pi \: \Omega$, the magnitude of average power density due to this antenna at a distance of $2$ km from the antenna (in $nW/m^2$) is _________.
asked
Mar 26, 2018
in
Electromagnetics
by
Milicevic3306
(
15.8k
points)
gate2014ec4
numericalanswers
electromagnetics
impedance
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