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

Given:

Charge on capacitor, q = 30 μC
Capacitance, C = 3 μF
Resistance, R = 5 MΩ

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Step 1: Find initial voltage across the capacitor

V = q / C

V = (30 × 10⁻⁶) / (3 × 10⁻⁶)

V = 10 V

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Step 2: Calculate initial current using Ohm’s Law

I = V / R

I = 10 / (5 × 10⁶)

I = 2 × 10⁻⁶ A

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Step 3: Convert current to microampere

I = 2 μA

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Final Answer:

The initial current flowing through the resistor is,
x = 2 μA