Electromagnetic Field Theory MCQs with Answers 2027

Q141

The electric field component of a wave in free space is given by E = 50sin(10₇t + kz)

j^

V/m. Which one of the following is the correct inference that can be drawn from this expression?

Select an option to see the answer and solution.

Q142

Open question

The current flowing through a wire of length 2.5 cm is 100 A. If wire is bent into a square, magnetizing force at the centre of square is

Select an option to see the answer and solution.

Q143

Open question

If the potential, V = 4x + 2 volts, the electric field is:

Select an option to see the answer and solution.

Q144

Open question

Poynting vector P = E × H has the unit

Select an option to see the answer and solution.

Q145

Open question

Consider the following
For a lossless transmission line, we can write:
1. Z_in = -jZ₀ for a shorted line with

l

= λ/8
2. Z_in = ±j∞ for a shorted line with

l

= λ/4
3. Z_in = -jZ₀ for an open line with

l

= λ/2
4. Z_in = Z₀ for a matched line of any length
Select the correct answer using the options given below:

Select an option to see the answer and solution.

Q146

Open question

VSWR of a purely resistive load of normalized value n + j0 for n < 1 is:

Select an option to see the answer and solution.

Q147

Open question

The wave length of a 100 MHz electromagnetic wave propagating through a perfect non-magnetic dielectric with relative permittivity ε_r = 9 is

Select an option to see the answer and solution.

Q148

Open question

Match List-I with List-II for a transmission line with a series impedance Z = R + jωLΩ/m and a shunt admittance Y = G + jωC mho/m, and select the correct answer:

List-I (Parameters)	List-II (Values)
a. Characteristic impedance Z₀	1. $ZY$
b. Propagation constant γ	2. $\frac{Z}{Y}$
c. The sending-end input impedance Z_S when the line is terminated in its characteristic impedance Z₀	3. $\frac{Y}{Z}$

Select an option to see the answer and solution.

Q149

Open question

Refraction of radio waves in the atmosphere results due to:

Select an option to see the answer and solution.

Q150

Open question

The electric field on the surface of a perfect conductor is 2 V/m. The conductor is immersed in water with ∈ = 80 ∈₀. The surface charge density on the conductor is

(\in= \frac{10 ^{- 9}}{36 π}) F/m

Select an option to see the answer and solution.

Q151

Open question

The voltage reflection coefficient at the load end of a transmission line is

Select an option to see the answer and solution.

Q152

Open question

In air the lossless transmission line of length 50 cm with L = 10 μH/m, C = 40 pF/m is operated at 25 MHz. Its electrical path length is

Select an option to see the answer and solution.

Q153

Open question

For a wave travelling in negative Z direction the value of

\frac{Ey}{Hx}

is:

Select an option to see the answer and solution.

Q154

Open question

A coaxial-cable with an inner diameter of 1 mm and outer diameter of 2.4 mm is filled with a dielectric of relative permittivity 10.89. Given

μ_{0} = 4 π \times 1 0^{- 7} H/m, ε_{0} = \frac{10 ^{- 9}}{36 π} F/m .

The characteristic impedance of the cable is

Select an option to see the answer and solution.

Q155

Open question

The frequency of a sound wave is 25 Hz and its wavelength is 4 m. What is the distance travelled by the sound wave in 2?

Select an option to see the answer and solution.

Q156

Open question

From a solution of wave equation in a conducting medium we can determine various parameters. In the light of this, match List-I with List-II and select the correct answer using the options given below the lists:

List-I (Parameter)	List-II (Expression)
a. Propagation constant	1. $(\frac{2}{ω μ σ})^{\frac{1}{2}}$
b. Skin depth	2. $(\frac{ω μ _{0}}{2 σ})^{\frac{1}{2}}$
c. Sheet resistance	3. $(j ω μ_{0} σ)^{\frac{1}{2}}$
	4. $(\frac{ω μ _{0} σ}{2})^{- \frac{1}{2}}$

Select an option to see the answer and solution.

Q157

Open question

The mode used in the laboratory bench is

Select an option to see the answer and solution.

Q158

Open question

Consider a rectangular coordinate system (x, y, z) with unit vectors a_x, a_y and a_z. A plane wave travelling in the region z ≥ 0 with electric field vector E = 10cos(2 × 10⁸t + βz)a_y is incident normally on the plane at z = 0, where β is the phase constant. The region z ≥ 0 is in the free space and the region z < 0 is filled with a lossless medium (permittivity ε = ε₀, permeability µ = 4µ₀, where ε₀ = 8.85 × 10¹² F/m and µ₀ = 4π × 10^-7 H/m).
The value of the reflection coefficient is

Select an option to see the answer and solution.

Q159

Open question

If a right hand circularly polarised wave is incident on a perfect conductor. The reflected wave is:

Select an option to see the answer and solution.

Q160

Open question

The maximum usable frequency of an ionospheric layer at 60° incidence at with 8 MHz critical frequency is

Select an option to see the answer and solution.

Electromagnetic Field Theorypractice.

Electromagnetic Field Theory
practice.