A charge of $10$ esu is placed at a distance of $2 \mathrm{cm}$ from a charge of $40$ esu and $4 \mathrm{cm}$ from another charge of $-20$ esu. The potential energy of the charge $10$ esu is: (in ergs)

As shown in figure, on bringing a charge $Q$ from point $A$ to $B$ and from $B$ to $C$, the work done are $2$ joules and - $3$ joules respectively. The work done bringing the charge from $C$ to $A$ will be

In the fig. force on charge at A in the direction normal to BC will be: