# Electromagnetics (Test 4)

## Gate Exam : Ec Electronics And Communication Engineering

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| Electromagnetic |
Q.1
The magnitude of magnetic flux density at a point having normal distance d meters from an infinitely extended wire carrying current of l A is (in SI units). An infinitely extended wire is laid along the x-axis and is carrying current of 4 A in the +ve x direction. Another infinitely extended wire is laid along the y-axis and is carrying 2 A current in the +ve y direction µ0 is permeability of free space Assume to be unit vectors along x, y and z axes respectively. Assuming right handed coordinate system, magnetic field intensity, at coordinate (2,1,0) will be

A. B. C. D. 0 A/m
Answer : Option C
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Q.2
The current density in a medium is given by The total current and the average current density flowing through the portion of a spherical surface r = 0.8 m, are given, respectively, by
A. 15.09 A, 12.86 Am-2
B. 18.73 A, 13.65 Am-2
C. 12.86 A, 9.23 Am-2
D. 10.28 A, 7.56 Am-2
Answer : Option A
Explaination / Solution:
No Explaination.

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Q.3
If C is code curve enclosing a surface S , then magnetic field intensity , the current density and the electric flux density are related by
A. B. C. D. Answer : Option D
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Q.4
Match the following A. P-2, Q-1, R-4, S-3
B. P-4, Q-1, R-3, S-2
C. P-4, Q-3, R-1, S-2
D. P-3, Q-4, R-2, S-1
Answer : Option B
Explaination / Solution:
No Explaination.

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Q.5
It is given that X, X .... XM at M non-zero, orthogonal vectors. The dimension of the vector space spanned by the 2M vectors X, X, ....XM, - X, - X, ..... - Xis
A. 2M
B. M+
C. M
D.  dependent on the choice of X, X, ...XM
Answer : Option C
Explaination / Solution:

For two orthogonal vectors, we require two dimensions to define them and similarly for three orthogonal vector we require three dimensions to define them. 2M vectors are basically M orthogonal vector and we require M dimensions to define them.

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Q.6
The expression for an electric field in free space is where x, y, z represent the spatial coordinates, t represents time, and 𝜔,k are constants. This electric field
A. does not represent a plane wave
B. represents a circular polarized plane wave propagating normal to the z-axis
C. represents an elliptically polarized plane wave propagating along x-y plane.
D. represents a linearly polarized plane wave
Answer : Option C
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Q.7
Two semi-infinite dielectric regions are separated by a plane boundary at y=0. The dielectric constant of region 1 (y<0) and region 2 (y>0) are 2 and 5, Region 1 has uniform electric field are unit vectors along the x, y and z axes, respectively. The electric field region 2 is
A. B. C. D. Answer : Option A
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