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Electronics and Communication Engineering - Electronic Devices and Circuits

Exercise : Electronic Devices and Circuits - Section 5
6.
A series R-L circuit has R = 1 Ω and L = 1 H. It is excited by a V battery at t = 0. The steady state condition is reached at
t = 1 s
t = 0.1 s
t = 0 s
t = ∞
Answer: Option
Explanation:

i = 10 (1 - e-t). It reaches steadily state value at t = ∞

7.
The current source in figure, can be replaced by
a voltage source of 20 V in series with 5 ohm resistance
a voltage source of 16 V in series with 4 ohm resistance
a voltage source of 20 V in series with 4 Ω resistance
a voltage source of 16 V in series with 5 Ω resistance
Answer: Option
Explanation:

The parallel combination of 20 Ω and 5 Ω is 4 Ω. Therefore, strength of current source is 4 x 4 = 16 A and source resistance is 4 ohms.

8.
If the voltage across the last resistor is V, and all the resistor is unity. Then Vs is given by
8 V
4 V
13 V
0
Answer: Option
Explanation:

Let the last voltage is V1 = V, V2 = Voltage across both 1 Ω resistor

V + V = 2V

Current in shunt resistor = i

ia = ib + ic

2v + v 3v

V3 = ib x R + ia x R

3v + 2v = 5v

V4 = 5v + 8v = 13v.

9.
In figure, iL at t = 0+ is
0
I
infinite
Answer: Option
Explanation:

Inductance behaves as O.C. at t = 0+.

10.
In a purely inductive circuit, the current __________ the voltage by __________ .
lags, 0°
leads, 90°
lags, 90°
lags, 45°
Answer: Option
Explanation:

In inductive circuit current lags the voltage by 90°.

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