Electronics and Communication Engineering - Electromagnetic Field Theory MCQs Part 4

1.Which of the following laws of electromagnetic theory is associated with the force experienced by two loops of a wire carrying currents?

A. Maxwell's law
B. Coulomb's law
C. Ampere's law
D. Laplace's law

 Answer Option C

2.The intrinsic impedance of free space

A. increases with increase of frequency
B. decreases with increase of frequency
C. is independent of frequency
D. none

 Answer Option C

3.To couple a coaxial line to a parallel to wire line it is best to use a

A. slotted line
B. balun
C. directional coupler
D. quarter wave transformer

 Answer Option B

4.The shunt admittance of a transmission line is given by

A. γ = R + jωL
B. γ = R - jωL
C. γ = G + jωC
D. γ = jωGC

 Answer Option C

5.A dipole antenna was radiating with some excitation in free space radiating a certain amount of the power. If this antenna is immersed in a lake where water is non-dissipative but has a dielectric constant of 81, the radiated power with the same excitation will

A. decrease to finite non-zero value
B. remain the same
C. increase
D. decrease to zero

 Answer Option B

6.If short-circuited and open circuited impedances are 5 ohms and 20 ohms, then characteristic impedance is

A. 1 ohms
B. 10 ohms
C. 25 ohms
D. 100 ohms

 Answer Option B

7.Electric lines of force do not cross each other because

A. the lines of force mutually repel each other
B. the lines of force emanate from a point charge
C. the tangent to the line of force gives the direction of E and if they cross two tangents for E which is not possible
D. none of the above

 Answer Option C

8.A person with a receiver is 5 km away from the transmitter. What is the distance that this person must move further to detect at 3 dB decrease in signal strength?

A. 942 m
B. 2070 m
C. 4978 m
D. 5320 m

 Answer Option B

9.For free space propagation

A. γ = a + jβ
B. γ = jβ
C. γ = a
D. a = β = 0

 Answer Option A

10.SHF range is

A. 30 - 300 MHz
B. 300 - 3000 MHz
C. 3000 - 30000 MHz
D. 30000 - 300000 MHz

 Answer Option C


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