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Electronics and Communication Engineering - Exam Questions Papers

Exercise : Exam Questions Papers - Exam Paper 3
41.
A λ/4 long high frequency transmission line is terminated into one impedance ZR. If Z0 be the characteristic impedance of the line, then input impedance Zin is
ZoZR
Z2R/Zo
Z20/ZR
Infinity
Answer: Option
Explanation:

, here and

∴ [Here ZL = ZR].

42.
Find the power absorbed or delivered by each source:
a = -32 b = - 12 c = -80 d = -60
a = -32 b = - 12 c = 80 d = 60
a = 32 b = 12 c = -80 d = 60
a = -32 b = 12 c = 80 d = -60
Answer: Option
Explanation:

Source a : Power : 8 x (4) = - 32 W. Source A has delivered the power as it is. - ve.

Source b: Source B has absorbed power of + 12 W as power is positive

Source c: Source C has absorbed power of 5 x 16 = 80 W

Source d: Delivers power of 3 x ix x (5) = 3 x 4 x (- 5) = -60 W

Total power of the network is - 32 + 12 + 80 - 60 = 0 Watts.

43.
The function shown in figure, can represent a probability density function for A __________
A = 1/4
A = 1/6
A = 1/9
A = 1/2
Answer: Option
Explanation:

The condition for the probability density function d(x) isand is always non negative or the area under the curve f(x)is unity.

=> A x 6 +x 2 x 3A = 1

or 9A = 1 or A =.

44.
If the transfer function of the following network is

The value of the load resistance RL is
R/4
R/2
R
2R
Answer: Option
Explanation:

.

45.
A bipolar differential amplifier uses a transistor having β0 = 200, ICQ = 100 mA, |Adm| = 500 and CMRR = 80 dB. The value of Rc and RE will be respectively __________ .
1.25 kΩ, 1.25 MΩ
125 kΩ, 1.25 MΩ
1.25 MΩ, 1.25 kΩ
3.25 kΩ, 3.25 MΩ
Answer: Option
Explanation:

80 = 20 log CMRR

∴ CMRR = 10000

But CMRR = 2gmRE

∴ = 1.25 MΩ

Adm = - gmRC

= 1.25 KΩ.

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