Recent questions and answers in Electromagnetics - GO Electronics

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GATE2017 EC-2: 55
The permittivity of water at optical frequencies is $1.75 \varepsilon _0$. It is found that an isotropic light source at a distance $d$ under water forms an illuminated circular area of radius $5$ m, as shown in the figure. The critical angle is $\theta _c$. The value of $d$ (in meter) is _______________

asked Nov 25, 2017 in Electromagnetics by admin (2.8k points)

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GATE2017 EC-2: 54
Standard air-filled rectangular waveguides of dimensions $a=2.29$ cm and $b=1.02 $ cm are designed for radar applications. It is desired that these waveguides operate only in the dominant $TE_{10}$ mode with the operating frequency at least $25 \%$ above the cutoff frequency of the $TE_{10}$ ... $6.55 \: GHz \leq f \leq 13.1 \: GHz$ $1.64 \: GHz \leq f \leq 10.24 \: GHz$

asked Nov 25, 2017 in Electromagnetics by admin (2.8k points)

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3

GATE2017 EC-2: 27
An integral $I$ over a counterclockwise circle $\textbf{C}$ is given by $I=\oint _c \frac{z^2-1}{z^2+1} e^z dz.$ If $\textbf{C}$ is defined as$\mid z \mid=3$ , then the value of $I$ is $-\pi i \sin(1)$ $- 2\pi i \sin(1)$ $-3\pi i \sin(1)$ $-4\pi i \sin(1)$

asked Nov 23, 2017 in Electromagnetics by admin (2.8k points)

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4

GATE2017 EC-2: 25
A two-wire transmission line terminates in a television set. The VSWR measured on the line is $5.8$. The percentage of power that is reflected from the television set is _________

asked Nov 23, 2017 in Electromagnetics by admin (2.8k points)

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5

GATE2017 EC-2: 24
Two conducting spheres $S1$ and $S2$ of radii $a$ and $b$ ($b>a$) respectively, are placed far apart and connected by a long, thin conducting wire, as shown in the figure. For some charge placed on this structure, the potential and surface electric field on $S1$ ... $V_a=V_b$ and $E_a<E_b$ $V_a>V_b$ and $E_a>E_b$ $V_a=V_b$ and $E_a>E_b$ $V_a>V_b$ and $E_a=E_b$

asked Nov 23, 2017 in Electromagnetics by admin (2.8k points)

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6

GATE2017 EC-1: 55
A half wavelength dipole is kept in the $x-y$ plane and oriented along $45^{\circ}$ from the $x$-axis. Determine the direction of null in the radiation pattern for $0\leq \phi \leq \pi$. Here the angle $\theta (0\leq \theta \leq \pi )$ is measured from the $z$ ... $\theta =45^{o},\phi =90^{o}$ $\theta =90^{o},\phi =135^{o}$ $\theta =45^{o},\phi =135^{o}$

asked Nov 17, 2017 in Electromagnetics by admin (2.8k points)

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7

GATE2017 EC-1: 54
The expression for an electric field in free space is , $\textbf{E}=E_{0}( \hat{x}+\hat{y}+j2 \hat{z} )e^{-j( \omega t-kx+ky)}$ where $x,y,z$ represent the special coordinates, $t$ represents time, and $\omega,k$ ... wave propagating normal to the $z$-axis represents an elliptically polarized plane wave propagating along the $x - y$ plane represents a linearly polarized plane wave

asked Nov 17, 2017 in Electromagnetics by admin (2.8k points)

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8

GATE2017 EC-1: 53
An optical fiber is kept along the $\hat{z}$ direction. The refractive indices for the electric fields along $\hat{x}$ and $\hat{y}$ directions in the fiber are $n_{x}=1.5000$ and $n_{y}=1.5001$ ... wave is circularly polarized at the input of the fiber, the minimum propagation distance after which it becomes linearly polarized, in centimeters,is______________.

asked Nov 17, 2017 in Electromagnetics by admin (2.8k points)

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9

GATE2017 EC-1: 25
Consider a wireless communication link between a transmitter and a receiver located in free space, with finite and strictly positive capacity. If the effective areas of the transmitter and the receiver antennas, and the distance between them are all doubled, and everything else ... a factor of $2$ Decreases by a factor of $2$ Remains unchanged Decreases by a factor of $\sqrt{2}$

asked Nov 17, 2017 in Electromagnetics by admin (2.8k points)

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10

GATE2017 EC-1: 24
The voltage of an electromagnetic wave propagating in a coaxial cable with uniform characteristic impedance is $V(l)= e^{-\gamma l +j\omega t }$ Volts, where $l$ is the distance along the length of the cable in meters, $\gamma=(0.1+j40)m^{-1}$ is ... rad/s is the angular frequency. The absolute value of the attenuation in the cable in dB/meter is__________.

asked Nov 17, 2017 in Electromagnetics by admin (2.8k points)

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