Electronics and Communication Engineering - Exam Questions Papers

1. 

In the signal flow graph of figure below, the gain C/R will be :

A. 11/9
B. 22/15
C. 24/23
D. 44/23

Answer: Option D

Explanation:

Forward path gain

P1 = 2 x 3 x 4 ⇒ 24, P2 = 5, D1 = 1

D2 = - 3, L1 = - 2, L2 = - 3, L3 = - 4

Two non touching loop = L1 x L3 = - 2 x - 4 = 8

But if we take loop L4 into consideration then = 5 x -1 x - 1 x - 1 = -5

.


2. 

The resonant frequency of the circuit shown in figure is,

A. 1/22p Hz
B. 1/2p Hz
C. 1/4p Hz
D. 1/2p Hz

Answer: Option C

Explanation:

Leq = L1 + L2 + 2M

Leq = 1 + 2 + 2 x = 4 H

.


3. 

A short grounded vertical antenna has a length L which is 0.05λ at frequency f. If its radiation resistance at f is R ohms, then its radiation resistance at a frequency 2f will be

A. R/2Ω
B.
C. 2RΩ
D. 4RΩ

Answer: Option D

Explanation:

Rr = 80p2

Rrf2.


4. 

Which of the following is a solution to the differential equation ?

A. x(t) = 3e-t
B. x(t) = 2e-3t
C.
D. x(t) = 3t2

Answer: Option B

Explanation:

log x(t) = 3t

x(t) = K.e-3t

Thus option (B) satisfies the solution.


5. 

In the circuit shown, the device connected to Y5 can have address in the range

A. 2000 - 20FF
B. 2D00 - 2DFF
C. 2E00 - 2EFF
D. FD00 - FDFF

Answer: Option B

Explanation:


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