1
GATE ECE 2002
Subjective
+5
-0
The switch in Fig. has been in position $$1$$ for a long time and is then moved to position $$2$$ at $$t\, = \,0$$.

(a) Determine $${V_C}\left( {{0^ + }} \right)$$ and $${I_{_L}}\left( {{0^ + }} \right)$$
(b) Determine $${{d{V_C}\left( t \right)} \over {dt}}\,\,$$ at $$t\, = \,{0^ + }$$
(c) Determine $${{V_C}\left( t \right)}$$ for $$t > 0$$

2
GATE ECE 2001
Subjective
+5
-0
The circuit shown in Fig. is operating in steady-state with switch $${S_1}$$ closed. The switch $${S_1}$$ is opened at $$t\, = \,0$$.

(a) Find $${i_L}\left( {{0^ + }} \right)$$.
(b) Find $${e_1}\left( {{0^ + }} \right)$$.
(c) Using nodal equations and Laplace transform approach, find an expression for the voltage across the capacitor for all $$t\, = \,0$$.

3
GATE ECE 2000
Subjective
+5
-0
The network $$N$$ in Fig. consists only of two elements: a resistor of $$1\Omega$$ and an inductor of L Henry. $$A$$ $$5$$ $$V$$ source is connected at the input at $$t\, = \,0$$ seconds. The inductor current is zero at $$t\, = \,0$$. The output voltage is found to be $$5{e^{ - 3t}}\,\,V,$$ for $$t\, = \,0$$.

(a) Find the voltage transfer function of the network.
(b) Find L, and draw the configuration of the network.
(c) Find the impulse response of the network.

4
GATE ECE 1999
Subjective
+5
-0
In the circuit of figure, the switch $$'S'$$ has remained open for a long time. The switch closes instantaneously at $$t = 0$$. n

(a) Find $${V_0}$$ for $$t \le 0$$ and as $$t \to \infty$$.
(b) Write an expression for $${V_0}$$ as a function of time for $$0 \le t \le \infty$$.
(c) Evaluate $${V_0}$$ at $$t = 25\,\,\mu$$sec.

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