A particle of mass $m$ and charge $q$ is placed at rest in a uniform electric field $E$ and then released. The kinetic energy attained by the particle after moving a distance $y$ is

${\rm{ }}1\,ne\,V{\rm{ }} = {\rm{ }}......\,J.$ (Fill in the gap)

Three charges $-q, Q$ and $-q$ are placed respectively at equal distances on a straight line. If the potential energy of the system of three charges is zero, then what is the ratio of $Q: q$ ?

A circle of radius $R$ is drawn with charge $+ q$ at the centre. A charge $q_0$ is brought from point $B$ to $C$, then work done is

For equal point charges $Q$ each are placed in the $xy$ plane at $(0, 2), (4, 2), (4, -2)$ and $(0, -2)$. The work required to put a fifth change $Q$ at the origin of the coordinate system will be

A proton has a mass $1.67 \times 10^{-27} \,kg$ and charge $+1.6 \times 10^{-19} \,C$. If the proton is accelerated through a potential difference of million volts, then the kinetic energy is ......... $J$