Electronics and Communication Engineering - Networks Analysis and Synthesis

1. 

The circuit in figure, is to be scaled to an impedance level of 5kΩ and resonant frequency of 5 x 106 rad/sec. The possible combination of R, L, C is

A. 2.5Ω, 0.2 mH, 200 pF
B. 5 kΩ, 0.2 mH, 200 pF
C. 5 kΩ, 0.2 mH, 200 μF
D. 5 kΩ, 0.1 mH, 0.4 μF

Answer: Option B

Explanation:

If L = 0.2 mH and C = 200 pF, ω0 = 5 x 106 rad/sec and if R is 5 kΩ, impedance level is 5 kΩ.


2. 

In figure, the total power consumed is

A. 10 W
B. 12 W
C. 16 W
D. 20 W

Answer: Option A

Explanation:

Use superposition theorem.


3. 

If operator 'a' = 1 ∠120° then (1 + a) =

A. -a
B. -a2
C. a
D. -1

Answer: Option B

Explanation:

Since 1 + a + a2 = 0, 1 + a = - a2.


4. 

A current wave is i = 100e-60t The initial and final values of current are

A. 100 and 50
B. 100 and 0
C. 0 and 100
D. 100 and 100

Answer: Option B

Explanation:

i(0) = 100 e-0 = 100, i(∞) = 100 e-∞ = 0.


5. 

Assertion (A): The impedance of a series resonant circuit is minimum at resonance.

Reason (R): Resonance condition implies unity power factor condition.

A. Both A and R are true and R is correct explanation of A
B. Both A and R are true and R is not the correct explanation of A
C. A is true but R is false
D. A is false but R is true

Answer: Option A

Explanation:

Since power factor is unity, impedance is minimum.


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