Electronics and Communication Engineering - Exam Questions Papers

46. 

System is at rest for t < 0. Vs = sin 2t. Determine v(t) for t greater than zero.

A.
B.
C.
D.

Answer: Option D

Explanation:

KCL at node V

Natural response from s + 2, is Ae-2t

For Vs = sin 2t, s = 2j

Steady state response

Since the system is at rest for t < 0

Now substituting t = 0, we get


47. 

A 300 MHz plane EM wave is propagating in free space. The wave is incident normally on an infinite copper slap. The antenuation constant for the wave is (σcopper = 5.8 x 107 mho/ m). The skin depth is

A. 0.005 x 10-3 m
B. 0.0038 x 10-3m
C. 0.0028 x 10-3 m
D. 0.0024 x 10-3 m

Answer: Option B

Explanation:

.


48. 

Following figure represents

A. AND
B. OR
C. NAND
D. NOT

Answer: Option C

Explanation:

The output C is low only when A and B are both 1.


49. 

For parallel RLC circuit, which one of the following statements is NOT correct?

A. The bandwidth of the circuit deceases if R is increased
B. The bandwidth of the circuit remains same if L is increased
C. At resonance, input impedance is a real quantity
D. At resonance, the magnitude of input impedance attains its minimum value

Answer: Option D

Explanation:

Bandwidth =

Thus it is maximum at resonance.


50. 

The practical resonant circuit is shown in above figure. Find the expression for the resonant frequency ωo

A.
B.
C.
D. None of these

Answer: Option B

Explanation:

Rationalising,

Equating imaginary parts of numerator to 0,

.


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