Electromagnetic and Transmission Lines 5

Electronic Engineering MCQ Question Papers: ENTC, IT Interview Placement

Subject:  Electromagnetic and Transmission Lines 5

Part 5: List for questions and answers of Electro Magnetics & Transmission Line

Q1. The phenomenon of work done while moving a point charge in presence of an electric field is independent of _______

a) Position

b) Force

c) Path

d) All of the above

Q2. During the movement of a charge, potential energy undergoes _________

a) Expansion

b) Compression

d) Reflection

Q3. During the representation of relationship between flux density and electric field density, what would be the value of relative permittivity for air medium?

a) 0

b) 1

c) 8.85 x 10^-12 F/m

d) 8

Q4. If a negative charge is absent corresponding to Faraday’s experiment of concentric spheres, then where do the flux lines show termination?

a) At zero

b) At unity

c) At infinity

Q5. Which type of phenomenon is likely to occur, if two charges possess opposite sign?

a) Force of attraction

b) Force of repulsion

c) Force of stability

d) Force of equality

Q6. According to coulomb’s law, what do the force between two point charges proportional to?

b) Difference of charges

c) Product of charges

d) Integration of charges

Q7. In accordance to Newton’s law, if two bodies m1 & m2 are separated by a distance R,

then what would be the value of gravitational force between them?

a) m1m2 G/R^2

b) m1m2/R^2

c) m1m2 G2/R

d) (m1m2)^2 G/R

Q8. 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

a) 4°

b) 2°

c) 10°

d) 15°

Q9. Refractive index of glass is 1.5. Find the wavelength of a beam of light with a frequency of 1014 Hz in glass. Assume velocity of light is 3 x 10^8 m/sec in vacuum

a) 4 µm

b) 3 µm

c) 2 µm

d) 1 µm

Q10. The function f(x – vot) represent which of the following?

a) A stationary wave

b) A wave motion in forward direction

c) A wave motion in reverse direction

d) None of the above

Q11. 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

a) 196 W

b) 73 W

c) 36.5 W

d) 18.25 W

Q12. A rectangular metal waveguide filled with a dielectric of relative permittivity er = 4, has the inside dimensions 3 x 1.2 cm, the cut off frequency for the dominant mode is

a) 2.5 GHz

b) 5 GHz

c) `10 GHz

d) 12.5 GHz

Q13. Find the radiation resistance of an antenna of length ?/10 meter?

a) 8 O

b) 780 O

c) 7.8 O

d) 78 O

Q14. 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

a) 4 cm

b) 1 cm

c) 2 cm

d) 8 cm

Q15. The input impedance of short-circuited line of length l where λ /4 is less l is less than λ /2, is

a) resistive

b) inductive

c) capacitive

d) none of the above

Q16. A wave is propagated in a waveguide at frequency of 9 GHz and separation is 2 cm between walls Calculate group velocity for dominant mode

a) 1.8 x 10^8 m/sec

b) 5 x 10^8 m/sec

c) 3 x 10^8 m/sec

d) 1.5 x 10^8 m/sec

Q17. For F1 layer the maximum ionic density is 2.3 x 10^4 electrons per cc. The critical frequency for this layer will be

a) 1.36 MHz

b) 13.6 MHz

c) 136 MHz

d) 1360 MHz

Q18. A hollow rectangular waveguide has dimensions a = 2b. Calculate the amount of attenuation, if the frequency is 3 GHz, and b = 1 cm

a) 49

b) 47.33

c) 50.33

d) 50

Q19. Calculate the directivity of an antenna for ?E = 30°, ?H = 60

a) 46

b) 23

c) 50

d) 100

Q20. The phase angle corresponding to ?/4 in a standing-wave pattern is

a) 30°

b) 90°

c) 135°

d) 180°

Part 5: List for questions and answers of Electro Magnetics & Transmission Line