Sunday, May 1, 2016

Transient Analysis of AC and DC circuits - Topicwise GATE Questions on Network Theory (from 2003)

Common circuit for Questions 1 & 2:
Assume that the switch S is in position 1 for a long time and thrown to position 2 at t=0.

1. At t = 0+, the current i1 is
a) – V/2R
b) – V/R
c) – V/4R
d) Zero


 2. I1(s) and I2(s) are the Laplace Transforms of i1(t) and i2(t) respectively. The equations for the loop currents I1(s) and I2(s) for the same circuit shown, after the switch is brought from position 1 to position 2 at t = 0, are

Solution (1 & 2):

3. In the following cirucit, the switch S is closed at t = 0. The rate of change of current di(0+)/dt is given by

Solution :

4. The switch in the circuit shown was on position 'a' for a long time, and is moved to position 'b' at time t=0. The current i(t) for t > 0 is given by

Solution :

5. In the cirucit shown, the switch S is open for a long time and is closed at t = 0. The current i(t) for t ≥ 0+ is

Solution :

6. In the circuit shown below, the initial charge on the capacitor is 2.5 mC, with the voltage polarity as indicated. The switch is closed at time t = 0. The current i(t) at a time t after the switch is closed is

Solution :

7. In the figure shown, the ideal switch has been open for a long time.

If it is closed at t = 0, then the magnitude of the current (in mA) through the 4 kΩ resistor at t = 0+ is ____________

Solution :

8. In the circuit shown, the switch SW is thrown from position A to position B at time t=0. The energy (in µJ) taken from the 3 volts source to charge the 0.1 µF capacitor from 0 volts to 3 volts is

a) 0.3
b) 0.45
c) 0.9
d) 3
Solution :

9. In the circuit shown, switch SW is closed at t =0. Assuming zero initial conditions, the value of Vc(t) (in volts) at t = 1 sec is __________________

Solution :

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