Networks Analysis And Synthesis

Question: A series resonant circuit has R = 10 Ω, L = 1 μH and C = 1 mF. If R is increased to 20 Ω the resonant frequency
[A].

increases

[B].

decreases

[C].

remains constant

[D].

may increases or decreases

Answer: Option C

Explanation:

fr depends only on L and C.

Question: A two branch parallel tuned circuit has a capacitance C in one of the two branches and resistance R in second branchs. As C is decreased the dynamic resistance
[A].

increases

[B].

decreases

[C].

remains constant

[D].

may increases or decreases

Answer: Option A

Explanation:

Dynamic resistance = and increases as C is decreased.

Question: A two branch tuned circuit has a coil of resistance R and inductance L in one branch and capacitance C in the second branch. If R is increased, the dynamic resistance
[A].

decreases

[B].

increases

[C].

remains constant

[D].

may increases or decreases

Answer: Option B

Explanation:

Dynamic resistance = and increases as L is increased.

Question: In a series resonant circuit Q is more than 10. Then the lower half power frequency ω1, and resonant frequency ω0 are related as
[A].

ω1 = ω0 + bandwidth

[B].

ω1 = ω0 + 0.5 (bandwidth)

[C].

ω1 = ω0 – 0.5 (bandwidth)

[D].

ω1 = ω0 + bandwidth

Answer: Option C

Explanation:

No answer description available for this question.

Question: A two branch parallel tuned circuit has a coil of resistance 100 Ω and inductance 0.005 H in one branch and 10 nF capacitor in the second branch. At resonance frequency is
[A].

100 rad/sec

[B].

10000 rad/sec

[C].

1000 rad/sec

[D].

more than 10000 rad/sec

Answer: Option C

Explanation:

= = 44.67 x 104 rad/sec.

Question: A two branch parallel tuned circuit has a coil of resistance 100 Ω and inductance 0.005 H in one branch and 10 nF capacitor in the second branch. At resonance frequency, the dynamic resistance is
[A].

1 Ω

[B].

10 Ω

[C].

100 Ω

[D].

more than 100 Ω

Answer: Option D

Explanation:

Dynamic resistance =

Question: A two branch parallel tuned circuit has 100 Ω resistance and 0.1 H inductance in one branch and 10-6 F capacitor in the other. At resonance frequency, the dynamic resistance is
[A].

10 Ω

[B].

100 Ω

[C].

1000 Ω

[D].

10000 Ω

Answer: Option C

Explanation:

Dynamic resistance =

Question: In figure, the magnitude of V
[A].

must be more than that of Va

[B].

must be more than that of Vb

[C].

must be more than that of Va or Vb

[D].

can be equal to or less than or more than that of Va or Vb

Answer: Option D

Explanation:

V depends on magnitudes and phase angles of Va and Vb.

Question: In figure, the current I4 is
[A].

10 ∠0

[B].

5 ∠90°

[C].

5 ∠270°

[D].

10 ∠90°

Answer: Option B

Explanation:

I4 = I1 + I2 + I3

or I4 = 5∠90° + 5∠0 + 5∠180° = 5∠90°.

Question: In a series ac circuit a voltage of 20 V at 25 Hz causes a current of 0.20 A, while the same voltage at 75 Hz causes a current of 0.12 A. The circuit consists of
[A].

R and C in parallel

[B].

R and C in series

[C].

R and L in series

[D].

either (a) or (b)

Answer: Option B

Explanation:

As f increases impedance increases and current decreases in RL circuit.