Question

The circuit shown in the figure consists of a charged capacitor of capacity 3 µF and a charge of 30 µC. At time t=0, when the key is closed, the value of current flowing through the 5 MΩ resistor is 'x' µA. The value of 'x' to the nearest integer is __________.

Hint:

At the instant the switch is closed ($t=0$), a charged capacitor acts like a battery of voltage $V=Q/C$.

Answer 1

Correct Answer: 2

Step 1: Potential across capacitor $V = Q/C = 30 \mu C / 3 \mu F = 10 \text{ V}$.
Step 2: At $t=0$, current $I = V/R$.
Step 3: $I = \frac{10}{5 \times 10^6} = 2 \times 10^{-6} \text{ A} = 2 \mu A$.
Step 4: $x = 2$.