Question

In the circuit shown above, when the key $K$ is pressed at time $t=0$, which of the following statements about current $I$ in the resistor $AB$ is true

• A. $I=2mA$ at all $t$
• B. $I$ oscillates between $1mA$ and $2mA$
• C. $I=1mA$ at all $t$
• D. At $t=0$, $I=2mA$ and with time it goes to $1mA$

Answer 1

The correct option is D At $t=0$, $I=2mA$ and with time it goes to $1mA$

When k is pressed at $t=0$, the capacitor will start charging through resistor in between A and B and no current will flow through resistor on the right.

Thus, at $t=0$ the current , $I=\frac{2}{1000}=2mA$.

After long time the charging will stop and current will flow through both resistors.

now current is $I=\frac{2}{1000+1000}=1mA$.