Electromagnetic - Online Test
Q1. A magnetic field in air is measured to be 
What current distribution leads to this field ?
What current distribution leads to this field ?[Hint : The algebra is trivial in cylindrical coordinates.]
Answer : Option C
Explaination / Solution:
Q2. The divergence of the vector field 
Answer : Option D
Explaination / Solution:
Given, the vector field
Q3. 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?
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?
Answer : Option C
Explaination / Solution:
Power radiated from any source is constant.
Q4. Consider a closed surface S surrounding volume V. If 
is the position vector
of a point inside S, with 
the unit normal on S, the value of the integral 
is
is the position vector
of a point inside S, with the unit normal on S, the value of the integral is
Answer : Option D
Explaination / Solution:
From Divergence theorem, we have
The position vector
Here, 
, thus
, thus
Q5. A current sheet 
lies on the dielectric interface x = 0
between two dielectric media with εr1 = 5, μr1 = 1 in Region -1 (x < 0) and εr2 = 5, μr2 = 2 in Region -2(x > 0) . If the magnetic field in Region-1 at
x = 0- is 
the magnetic field in Region-2 at x = 0+ is
lies on the dielectric interface x = 0
between two dielectric media with εr1 = 5, μr1 = 1 in Region -1 (x < 0) and εr2 = 5, μr2 = 2 in Region -2(x > 0) . If the magnetic field in Region-1 at
x = 0- is the magnetic field in Region-2 at x = 0+ is
Answer : Option A
Explaination / Solution:
From boundary condition
Then from Boundary condition
Comparing we get A = 30 and B =- 10
Q6. The electric and magnetic fields for a TEM wave of frequency 14 GHz in a
homogeneous medium of relative permittivity εr and relative permeability
Assuming the speed of light in free space to be 3 × 108 m/s, the intrinsic
impedance of free space to be 120π, the relative permittivity εr of the medium
and the electric field amplitude Ep are
Answer : Option D
Explaination / Solution:
From the expressions of 
we can write,
we can write,
Q7. 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
The total current and the average current density flowing through the portion of a spherical
surface r = 0.8 m, are given, respectively, by
Answer : Option A
Explaination / Solution:
No Explaination.
