When the key K is pressed at time t=0, then which of the following statement about the current I in the resistor AB of the given circuit is true? (a) I oscillates between 1 mA and 2 mA (b) at t=0, I=2 mA and with time it goes to 1 mA (c) I=1 mA at all t (d) I=2 mA at all t

Answer: (b). At t=0 the uncharged capacitor acts as a short across the right 1000 Ω: I = 2/1000 = 2 mA. In steady state the capacitor is open: I = (2)/(1000+1000) = 1 mA. So the answer is (b): 2 mA at t=0, falling to 1 mA.

When the key K is pressed at time t=0, then which of the following… | NEET 1995 (AIPMT)

Q45NEET 1995 · AIPMTMedium

Capacitors in DC Circuits & RC

When the key $K$ is pressed at time $t=0$ , then which of the following statement about the current $I$ in the resistor $AB$ of the given circuit is true?

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Answer: (b)

At $t=0$ the uncharged capacitor acts as a short across the right $1000\ \Omega$ : $I = \dfrac{2}{1000} = 2\text{ mA}$ .
In steady state the capacitor is open: $I = \dfrac{2}{1000+1000} = 1\text{ mA}$ .
So the answer is (b): 2 mA at $t=0$ , falling to 1 mA.

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