Electronics And Communication Engineering

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

by
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.

In a series L-C circuit fed by ac voltage, voltage drops across L and C are 40 V and 30 V respectively. The supply voltage is

by
Question: In a series L-C circuit fed by ac voltage, voltage drops across L and C are 40 V and 30 V respectively. The supply voltage is
[A].

70 V

[B].

10 V

[C].

50 V

[D].

1.333 V

Answer: Option C

Explanation:

|V| = IXL – IXC.

In class C operation of an amplifier circuit, the collector current exists for

by
Question: In class C operation of an amplifier circuit, the collector current exists for
[A].

360° of input wave

[B].

180° of input wave

[C].

more than 180° of input wave

[D].

less than 180° of input wave

Answer: Option D

Explanation:

In class C operation output is in the form of short duration pulses.

A current 10 sin (200t) A flows through a 5 mH inductance. The expression for voltage is

by
Question: A current 10 sin (200t) A flows through a 5 mH inductance. The expression for voltage is
[A].

10 sin (200t + 90°)

[B].

10 sin (200t – 90°)

[C].

10 sin(1000t + 90°)

[D].

10 sin (1000t – 90°)

Answer: Option D

Explanation:

Z = jXL = jωL = = 1∠90° and V = IXL