Revision quiz on Communication System for JEE & BITSAT Exams

Question 1

A radar has a power of 1 Kw and is operating at a frequency of 10 GHz. It is located on a mountain top of height 500m. The maximum distance (in km) upto which it can detect object located on the surface of the earth (Radius of earth =

is

Question 2

If the lattice constant of this semiconductor is decreased, then which of the following is correct ?

Question 3

The heights of a transmitting antenna and a receiving antenna are 40 m and 60 m, respectively. The maximum distance between them for satisfactory communication in line of sight mode is

Question 4

For amplitude modulated transmission a band width of 20 MHz is used. If the audio signal modulating is less than 20 kHz, then the number of stations that can be broadcasted within this band is

Question 5

What will be the modulating index of an audio signal having the amplitude one half of career Amplitude.

Question 6

An amplitude modulated wave is represented by the expression

. Find the ratio of maximum amplitude to minimum amplitude of the amplitude modulated wave.

Question 7

If the maximum and minimum voltage for an amplitude modulated wave are 150 V and 75 V respectively. Then find the ratio of amplitudes of carrier and signal wave.

Question 8

The number of amplitude modulated broadcast stations that can be accommodated in a 300 kHz band width for the highest modulating frequency 15 kHz will be :

Question 9

A transmitting antenna at the top of a tower has a height 40 m and the height of the receiving antenna is 70 m. What is the maximum distance of them for satisfactory communication in the line of sight mode?

Question 10

An electromagnetic wave travelling in the x-direction has frequency of

and electric field amplitude of

. From the options given below, which one describes the magnetic field for this wave?

Question 11

A 100 m long TV transmission tower is placed in a metro area of United State of America. How much population is covered by the transmission if the average population density around the tower is 4000 km^-2 ? Assume the radius of earth is 6400 km.

Question 12

A signal of frequency 20 kHz and peak voltage of 5 Volt is used to modulate a carrier wave of frequency 1.2 MHz and peak voltage 25 Volts. Choose the correct statement.

Question 13

In amplitude modulation, sinusoidal carrier frequency used is denoted by

and the signal frequency is denoted by

. The bandwidth

of the signal is such that

. Which of the following frequencies is not contained in the modulated wave?

Question 14

Sinusoidal carrier voltage of frequency 1.5 MHz and amplitude 50V is amplitude modulated by sinusoidal voltage of frequency 10 kHz producing 50% modulation. The lower and upper-side-band frequencies in kHz are

Question 15

The modulation index of an FM is 0.35. If modulating frequency is 5 kHz, the maximum deviation of frequency would be