Find the current from the battery at $(i)$ $t \rightarrow 0$ (initial) and $(ii)$ $t \rightarrow \infty$ (after a long time) when the switch is closed at $t = 0$.

Find the charge on the capacitor $C$ in the following circuit in $\mu C$.

The plates of a capacitor are charged to a potential difference of $320 \, V$ and are then connected across a resistor. The potential difference across the capacitor decays exponentially with time. After $1 \, s$ the potential difference between the plates of the capacitor is $240 \, V$,then after $2 \, s$ and $3 \, s$ the potential difference between the plates will be:

At time $t=0$,a battery of $10 \ V$ is connected across points $A$ and $B$ in the given circuit. If the capacitors have no charge initially,at what time (in seconds) does the voltage across them become $4 \ V$? [Take $\ln 5=1.6, \ln 3=1.1$]

The circuit shown in the figure consists of a charged capacitor of capacity $3\, \mu F$ and a charge of $30\, \mu C$. At time $t = 0,$ when the key is closed,the value of current flowing through the $5\, M\Omega$ resistor is $'x'\, \mu A$. The value of $'x'$ to the nearest integer is .........

$A$ filter circuit used in a rectifier has a load resistance of $200 \Omega$ and a capacitance of $15 \mu\text{F}$. The value of the time constant is . . . . . . .