Communications
Topic: Communication Systems
Tag: CBSE 12TH PHYSICS
Q.1
Electronic communication refers to
A. transfer of information encoded in electrical signals
B. transfer of information or messages encoded in electrical signals
C. transfer of electricity from one point to another
D. transfer of messages encoded in electrical signals
Answer : Option B
Explaination / Solution:
When information are sent from one point to the other it has to be converted into electrical signal using transducer.The receiver receives it in its original from using receiver.Such from of communication is called electronic communication.
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Topic: Communication Systems
Tag: CBSE 12TH PHYSICS
Q.2
Any physical quantity like temperature can be converted to
A. Analog or digital electrical signal
B. only analog electrical signal
C. constant electrical voltage
D. only digital electrical signal
Answer : Option A
Explaination / Solution:
An electrical transducer is a device which is capable of converting the physical quantity into a proportional electrical quantity such as voltage or electric current. Hence it converts any quantity to be measured into usable electrical signal. This physical quantity which is to be measured can be pressure, level, temperature, displacement etc. The output which is obtained from the transducer is in the electrical form and is equivalent to the measured quantity. For example, a temprature transducer will convert temperature to an equivalent electrical potential. This output signal can be used to control the physical quantity or display it.moreover this is of two type Digital or Analog electrical signals.
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Topic: Communication Systems
Tag: CBSE 12TH PHYSICS
Q.3
Bandwidth of an electronic communication system
A. is the minimum frequency at which an equipment
B. is the maximum frequency at which an equipment
C. is the frequency range over which an equipment operates or the portion of the spectrum occupied by the signal
D. is number of bands in the spectrum
Answer : Option C
Explaination / Solution:
A range within a band of wavelengths, frequencies, or energies; especially : a range of radio frequencies which is occupied by a modulated carrier wave, which is assigned to a service, or over which a device can operate.
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Topic: Communication Systems
Tag: CBSE 12TH PHYSICS
Q.4
for a signal to be reproduced without distortion
A. All the harmonics should be present
B. none of these
C. only the fundamental is required
D. only the fundamental and first harmonic is required
Answer : Option A
Explaination / Solution:
No Explaination.
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Topic: Communication Systems
Tag: CBSE 12TH PHYSICS
Q.5
To increase the range of line of sight communication
A. decrease the height of transmitting tower only
B. increase the height of both transmitting and receiving towers
C. decrease the height of both transmitting and receiving towers
D. decrease the height of receiving tower only
Answer : Option B
Explaination / Solution:
No Explaination.
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Topic: Communications
Tag: EC GATE 2007
Q.6
If R(τ) is the auto correlation function of a real, wide-sense stationary random process, then which of the following is NOT true
A. 
B. 
C. 
D. The mean square value of the process is R(0)
Answer : Option C
Explaination / Solution:
No Explaination.
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Topic: Communications
Tag: EC GATE 2007
Q.7
A load of 50 Ω is connected in shunt in a 2-wire transmission line of Z0 = 50Ω as shown in the figure. The 2-port scattering parameter matrix (s-matrix) of the
shunt element is
A. 
B. 
C. 
D. 
Answer : Option C
Explaination / Solution:
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Topic: Communications
Tag: EC GATE 2008
Q.8
A memory less source emits n symbols each with a probability p. The entropy of the source as a function of n
A. increases as log n
B. decreases as log(1/n )
C. increases as n
D. increases as nlogn
Answer : Option A
Explaination / Solution:
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Topic: Communications
Tag: EC GATE 2009
Q.9
A white noise process X(t) with two-sided power spectral density 1 X 10-10 W/HZ is input to a filter whose magnitude squared response is shown below.
A.
5 X 10-10 W
B.
1 X 10-6 W
C.
2 X 10-6 W
D.
1 X 10-5 W
Answer : Option C
Explaination / Solution:
No Explaination.
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Topic: Communications
Tag: EC GATE 2009
Q.10
For a message signal 
and carrier of frequency fc which of thefollowing represents a single side-band (SSB) signal ?
A. 
B. 
C. 
D. 
Answer : Option C
Explaination / Solution:
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