Physics Electrostatic Potential and Capacitance

In the circuit shown in the figure, the total charge is 750 µC and the voltage across capacitor C? is 20 V. Then the charge on capacitor C? is

A 5µF capacitor is charged fully by a 220 V supply. It is then disconnected from the supply and is connected in series to another uncharged 2.5µF capacitor. If the energy change during the charge redistribution is X/100 J then value of X to the nearest integer is:

A parallel plate capacitor has plate of length ' $$ l', width ' w$$ ' and separation of plates is 'd $$ '. It is connected to a battery of emf V$$ . A dielectric slap of the same thickness 'd $$ ' and of dielectric constant $$ k = 4 is being, inserted between the plates of the capacitor. At what length of the slab inside plates, will be energy stored in the capacitor be two times the initial energy stored?

Ten charges are placed on the circumference of a circle of radius $10\mathrm{s}$ $$ with constant angular separation between successive charges. Alternate charges 1, 3, 5, 7, 9 have charge (+q)$$ each, while $\mathrm{2,4},\mathrm{6,8},10$ $$ have charge $$ (-q)each. The potential v$$ and the electric field $$ E at the centre of the circle are respectively: (Take V = 0 $$ at infinity)

In the circuit shown, charge on the $5\mu \mathrm{F}$ $$ capacitor is: