$A$ $2$ $\mu F$ capacitor is charged to a potential $=$ $10\,V$. Another $4$ $\mu F$ capacitor is charged to a potential $=$ $20\,V$. The two capacitors are then connected in a single loop, with the positive plate of one connected with negative plate of the other. What heat is evolved in the circuit?......$\mu J$

If there are $n$ capacitors in parallel connected to $V$ volt source, then the energy stored is equal to

The lower plate of a parallel plate capacitor is supported on a rigid rod. The upper plate is suspended from one end of a balance. The two plates are joined together by a thin wire and subsequently disconnected. The balance is then counterpoised. Now a voltage $V = 5000\, volt$ is applied between the plates. The distance between the plates is $d =5\, mm$ and the area of each plate is $A = 100 cm^2.$ Then find out the additional mass placed to maintain balance.......$g$ [All the elements other than plates are massless and nonconducting] :-

Two identical capacitors, have the same capacitance $C$. One of them is charged to potential ${V_1}$ and the other to ${V_2}$. The negative ends of the capacitors are connected together. When the positive ends are also connected, the decrease in energy of the combined system is

If the plates of a parallel plate capacitor connected to a battery are moved close to each other, then

$A$. the charge stored in it, increases.

$B$. the energy stored in it, decreases.

$C$. its capacitance increases.

$D$. the ratio of charge to its potential remains the same.

$E$. the product of charge and voltage increases.

Choose the most appropriate answer from the options given below:

A $20\,F$ capacitor is charged to $5\,V$ and isolated. It is then connected in parallel with an uncharged $30\,F$ capacitor. The decrease in the energy of the system will be.......$J$