The equivalent capacitance between points $A$ and $B$ is

The equivalent capacitance between $ A $ and $ B $ is,

Four capacitors with capacitances $C_1 = 1\ C$,$C_2 = 2\ C$,$C_3 = 3\ C$,and $C_4 = 4\ C$ are connected to a battery of potential $V$ as shown in the figure. Find the ratio of charges on $C_2$ and $C_4$.

In the circuit shown,a potential difference of $30\, V$ is applied across $AB$. The potential difference between the points $M$ and $N$ is....$V$

Two parallel plate capacitors are connected in series. Each capacitor has a plate area $A$ and a separation $d$ between the plates. The dielectric constants of the media between their plates are $2$ and $4$. The separation between the plates of a single air capacitor of plate area $A$ which effectively replaces the combination is:

In the given circuit,the charge on the $4\, \mu F$ capacitor will be.....$\mu C$.