Electronics and Communication Engineering - Communication Systems

41.
A generator is feeding power to a transmission line of characteristic impedance Z0. The line is terminated in impedance ZL. Standing waves will be set up if
ZL = Z0
ZL < Z0
ZL > Z0
both (b) and (c)
Answer: Option
Explanation:

Both the case, i.e., ZL > Z0 and ZL < Z0 give rise to standing waves.


42.
In sound recording the degree of pre-emphasis is about 6 dB/ octave.
True
False
Answer: Option
Explanation:

It erases the matter already existing on the tape.


43.
Space wave may be a direct wave or wave reflected from earth.
True
False
Answer: Option
Explanation:

Strength of space wave depends on distance as it suffers attenuation.


44.
Radio broadcasts are generally
amplitude modulation
frequency modulation
both amplitude and frequency modulation
neither amplitude nor frequency modulation
Answer: Option
Explanation:

Frequency modulation gives noise free reception and is used for radio broadcasts.


45.
If the frequency of a wave 20 Hz, the time period is
20 secs
2 secs
0.2 secs
0.05 secs
Answer: Option
Explanation:

.