Communications Question Bank

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1. The total power content of an AM wave is 1500\,W. For 100\% modulation, the power transmitted by the carrier is
A.
B.
C.
D.
2. The characteristic impedance  (Z_{0})  of free space is
A.
B.
C.
D.
3. The characteristic impedance of a coaxial cable if of the order of
A.
B.
C.
D.
4. To cover a population of 20lakh, transmission tower should have height…. (Radius of earth =6400\,km, population per square km=1000)
A.
B.
C.
D.
5. What is the minimum length antenna required to transmit a radio signal of frequency 20MHz ?
A.
B.
C.
D.
6. The rest mass of a body is m_{0}, if it moves with a velocity of 0.6c, then its relativity mass is m, then
A.
B.
C.
D.
7. A double star system consist of two star A and B which have time period T_{A} and T_{B}. Radius R_{4} and R_{B} and mass M_{A} and M_{B}. Choose the correct option
A.
B.
C.
D.
8. If sky wave with a frequency of 50\,MHz is incident on D region at an angle of 30^{o}, then angle of refraction is
A.
B.
C.
D.
9. In hydrogen spectrum, the wavelength of H_{\alpha} line is 6.56nm, whereas in the spectrum of a distant galaxy, H_{\alpha} wavelength is 706nm, Estimated speed of the galaxy with respect to earth is
A.
B.
C.
D.
10. Optical fibre works on the principle of
A.
B.
C.
D.