Electromagnetics - Online Test
Q1.
The electric field component of a time harmonic plane EM wave traveling in a nonmagnetic lossless dielectric medium has an amplitude of 1 V/m. If the relative permittivity of the medium is 4, the magnitude of the time-average power density vector (in W/m2) is
Answer : Option C
Explaination / Solution:
Intrinsic impedance of EM wave
Time average power density
Q2. Two infinitely long wires carrying current are as shown in the figure below. One wire is in the y - z plane and parallel to the y axis. The other wire is in the x - y plane and parallel to the x - axis. Which components of the resultingmagnetic field are non-zero at the origin ?
Answer : Option D
Explaination / Solution:
Due to 1 A current wire in x - y plane, magnetic field be at origin will be in x direction.
Due to 1 A current wire in y - z plane, magnetic field be at origin will be in z direction.
Thus x and z component is non-zero at origin.
Due to 1 A current wire in y - z plane, magnetic field be at origin will be in z direction.
Thus x and z component is non-zero at origin.
Q3. If a vector field 
is related to another vector field 
through 
which of the following is true? (Note : C and SC refer to any closed contour and any surface whose boundary is C . )
is related to another vector field through which of the following is true? (Note : C and SC refer to any closed contour and any surface whose boundary is C . )
Answer : Option B
Explaination / Solution:
Hence (B) is correct option.
Q4. A plane wave having the electric field components 
V/m and traveling in free space is incident normally on a lossless medium with 
which occupies the region y ≥ 0. The reflected magnetic field component is given by
V/m and traveling in free space is incident normally on a lossless medium with which occupies the region y ≥ 0. The reflected magnetic field component is given by
Answer : Option A
Explaination / Solution:
In the given problem
Reflection coefficient
negative So magnetic field component does not change its direction Direction of incident magnetic field
So, reflection magnetic field component
Q5. 
The silicon sample with unit cross-sectional area shown below is in thermal equilibrium. The following information is given: T = 300 K electronic charge = 1.6 × 10-19 C, thermal voltage = 26 mV and electron mobility = 1350 cm2 / V-s
The magnitude of the electric field at x = 0.5 μm is
Answer : Option C
Explaination / Solution:
No Explaination.
Q6. 
The silicon sample with unit cross-sectional area shown below is in thermal equilibrium. The following information is given: T = 300 K electronic charge = 1.6 × 10-19 C, thermal voltage = 26 mV and electron mobility = 1350 cm2 / V-s
The magnitude of the electron of the electron drift current density at x = 0.5 μm is
Answer : Option A
Explaination / Solution:
Electron drift current density
Q7. 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
where x, y, z represent the spatial coordinates, t represents time, and 𝜔,k are constants. This electric field
Answer : Option C
Explaination / Solution:
Q8.
Consider a straight, infinitely long, current carrying conductor lying on the z-axis. Which one of the following plots (in linear scale) qualitatively represents the dependence of Hϕ on r , where Hϕ is the magnitude of the azimuthal component of magnetic field outside the conductor and r is the radial distance from the conductor ?
Answer : Option C
Explaination / Solution:
No Explaination.
Q9. A vector 
is given by 
Which one of the following statements is TRUE?
is given by Which one of the following statements is TRUE?
Answer : Option A
Explaination / Solution:
Given vector,
If divergence 
then vector 
is solenoidal. So, we obtain
then vector is solenoidal. So, we obtainHence, it is solenoidal.
Again, if curl 
then 
is irrotational. So, we obtain
then is irrotational. So, we obtain
Q10. The force on a point charge +q kept at a distance d from the surface of an infinite grounded metal plate in a medium of permittivity 𝜖 i
Answer : Option C
Explaination / Solution:
Consider the point charge +q and infinite surface as shown below.
We can replace the image charge by a negative equivalent charge -q placed at
2d distance from +q charge
Hence, the force experienced by +q charge is
