# Electromagnetic Fields (Test 2)

## Gate Exam : Ee Electrical Engineering

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Electromagnetic Fields
| Electromagnetic |
Q.1
Consider an electron, a neutron and a proton initially at rest and placed along a straight line such that the neutron is exactly at the center of the line joining the electron and proton. At t=0, the particles are released but are constrained to move along the same straight line. Which of these will collide first?
A. The particles will never collide
B. All will collide together
C. Proton and Neutron
D. Electron and Neutron
Explaination / Solution:

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Q.2
A magnetic field in air is measured to be What current distribution leads to this field ?
[Hint : The algebra is trivial in cylindrical coordinates.]

A.
B.
C.
D.
Explaination / Solution:

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Q.3
A solid iron cylinder is placed in a region containing a uniform magnetic field such that the cylinder axis is parallel to the magnetic field direction. The magnetic field lines inside the cylinder will
A. bend closer to the cylinder axis
B. bend farther away from the axis
C. remain uniform as before
D. cease to exist inside the cylinder
Explaination / Solution:

Flux always chooses less reluctance path. So flux tried to flow inside the conductor and closer to the axis of the cylinder.

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Q.4
A uniform plane wave in the free space is normally incident on an infinitely thick dielectric slab (dielectric constant ε = 9). The magnitude of the reflection coefficient is
A. 0
B. 0.3
C. 0.5
D. 0.8
Explaination / Solution:

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Q.5
The divergence of the vector field
A. 0
B. 1/3
C. 1
D. 3
Explaination / Solution:

Given, the vector field

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Q.6
Given a vector field  the line integral ∫ F.dl evaluated along a segment on the x-axis from x=1 to x=2 is
A. -2.33
B. 0
C. 2.33
D. 7
Explaination / Solution:
No Explaination.

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Q.7
Consider the following statements regarding the complex Poynting vector  for the power radiated by a point source in an infinite homogeneous and lossless medium. Re() denotes the real part of  denotes a spherical surface whose centre is at the point source, and denotes the unit surface normal on S. Which of the following statements is TRUE?
A. Re() remains constant at any radial distance from the source
B.  Re() increases with increasing radial distance from the source
C.   remains constant at any radial distance from the source
D.   decreases with increasing radial distance form the source
Explaination / Solution:

Power radiated from any source is constant.

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Q.8
Divergence of the three-dimensional radial vector field  is
A. 3
B. 1/r
C.
D.
Explaination / Solution:
No Explaination.

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Q.9
The curl of the gradient of the scalar field defined by V = 2x2y + 3y2z + 4z2x is
A.
B.
C.
D. 0
Explaination / Solution:
No Explaination.

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Q.10
The flux density at a point in space is given by  The value of constant k must be equal to
A. -2
B. -0.5
C. +0.5
D. +2