The radius of a soap bubble whose potential is $16\,V$ is doubled. The new potential of the bubble will be.....$V$

If $3$ charges of magnitude $q$ each are placed at the vertices of an equilateral triangle of side $l \ cm$,what is the net potential energy of the system?

$A$ positively charged ring is in the $y-z$ plane with its centre at the origin. $A$ positive test charge $q_0$,held at the origin,is released along the $x$-axis. Then its speed

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

An electron of charge $e$ coulomb passes through a potential difference of $V$ volts. Its energy in joules will be

$A$ bullet of mass $2\,g$ has a charge of $2\,\mu C$. Through what potential difference must it be accelerated, starting from rest, to acquire a speed of $10\,m/s$?