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Electromagnetic Field Theory Online Exam Quiz

Important questions about Electromagnetic Field Theory. Electromagnetic Field Theory MCQ questions with answers. Electromagnetic Field Theory exam questions and answers for students and interviews.

3. Characteristic impedance of a transmission line is 50 ?. Input impedance of the open circuited line. Z oc = 100 + J150 ?. When transmission line is short circuited, then value of the input impedance will be

Options

A : 50 ?

B : 100 + J150 ?

C : 7.69 + J11.54?

D : 7.69 - J11.54 ?

4. The input impedance of short-circuited line of length l where ?/4 < l < ?/2, is

Options

A : resistive

B : inductive

C : capacitive

D : none of the above

5. Z L = 200 ? and it is desired that Z i = 50 ? The quarter wave transformer should have a characteristic impedance of

Options

A : 100 ?

B : 40 ?

C : 10000 ?

D : 4 ?

6. For F 1 layer the maximum ionic density is 2.3 x 10 4 electrons per cc. The critical frequency for this layer will be

Options

A : 1.36 MHz

B : 13.6 MHz

C : 136 MHz

D : 1360 MHz

7. A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls calculate the phase velocity for dominant mode.

Options

A : 3 x 10 8 m/sec

B : 5 x 10 8 m/sec

C : 1.5 x 10 8 m/sec

D : 9 x 10 8 m/sec

8. A plane wave is characterized by the wave is

Options

A : linearly polarized

B : circularly polarized

C : elliptically polarized

D : unpolarized

10. What is the characteristic impedance at 10 MHz?

Options

A : 547.7 ?

B : 54.7 ?

C : 5.47 ?

D : .547 ?

1. The displacement flux density at a point on the surface of a perfect conductor is = 2( a x - 3 a z )c/m 2 pointing away from the surface. The charge density at that point c/m 2 will be

Options

A : 2

B : - 2

C : 4

D : - 4

2. The velocity of electromagnetic wave in a good conductor is

Options

A : 3 x 10 8 m/s

B : more than 3 x 10 8 m/s

C : very low

D : high

4. A parallel polarized wave is incident from air into paraffin having relative permittivity 3, the value of its Brewster angle is

Options

A : 0°

B : 30°

C : 45°

D : 60°

5. For a 400 kHz transmission line having L = 0.5 mH/km, C = 0.08 mF and negligible R and G, the value of propagation constant P will be

Options

A : 15.9 radians/km

B : 31.8 radians/km

C : 63.6 radians/km

D : 105.4 radians/km

6. The Depth of penetration of EM wave in medium having conductivity ? at a frequency of 1 MHz is 25 cm. The depth of penetration at a frequency of 4 MHz will be

Options

A : 6.25 cm

B : 12.50 cm

C : 50 cm

D : 100 cm

8. The divergence of the electric field intensity at any point equals

Options

A : 1/4 p ? 0 times the volume charge density

B : l/? 0 times the volume charge density at that point

C : ? 0 times the volume charge density at that point

D : the volume charge density at that point

9. A broadside array operating at 100 cm wavelength consist of 4 half-wave dipoles spaced 50 cm apart. Each element carries radio frequency current in the same phase and of magnitude 0.5 A. The radiated power will be

Options

A : 196 W

B : 73 W

C : 36.5 W

D : 18.25 W

10. A rectangular metal waveguide filled with a dielectric of relative permittivity ? r = 4, has the inside dimensions 3 x 1.2 cm, the cut off frequency for the dominant mode is

Options

A : 2.5 GHz

B : 5 GHz

C : 10 GHz

D : 12.5 GHz

2. Calculate the directivity of an antenna for ? E = 30°, ? H = 60

Options

A : 46

B : 23

C : 50

D : 100

3. A broadside array consisting of 200 cm wavelength with 10 half-wave dipole spacing 10 cm. And if each array element feeding with 1 amp. current and operating at same frequency then find the half power beamwidth

Options

A : 4°

B : 2°

C : 10°

D : 15°

4. A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls find cut off wavelength for dominant mode.

Options

A : 4 cm

B : 1 cm

C : 2 cm

D : 8 cm

5. A (75 - j 40) W load is connected to a co-axial line of z 0 = 75? at 6 MHz. The load matching on the line can be accomplished by connecting

Options

A : a short circuit stub at the load

B : an inductance at the load

C : a short circuit stub at a specific distance from the load

D : a capacitance at a specific distance from the load

7. The electric field on the surface of a perfect conductor is 2V/m. The conductor is immersed in water with ? = 80 ? 0 . The surface charge density on the conductor is ((? 0 = 10 -9 /36 p )F/m)

Options

A : 0 c/m 2

B : 2 c/m 2

C : 1.8 x 10 -11 c/m 2

D : 1.14 x 10 -9 c/m 2

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