The capacity of a pure capacitor is $1 \, F$. In $DC$ circuits,its effective resistance will be

In a $CR$ circuit, the growth of charge on the capacitor is

In an $RC$ circuit as shown below,both switches are open initially. Now switch $S_1$ is closed and $S_2$ is kept open. ($q$ is the charge on the capacitor and $\tau = RC$ is the capacitive time constant). Which of the following statements is correct?

$A$ capacitor is connected to a cell of $emf$ $E$ having some internal resistance $r$. The potential difference across the

The time constant of the given circuit is:

$A$ $30\,\mu F$ capacitor is charged by a constant current of $30\, mA$. If the capacitor is initially uncharged,how long does it take for the potential difference to reach $400\, V$?