Two particles of equal mass $m$ and equal charge $q$ are separated by a distance of 16 cm . They do not experience any force. The value of $\frac{q}{m}$ is (if $G$ is the universal gravitational constant and $g$ is the acceleration due to gravity)

In the following diagram, the work done in moving a point charge from point $P$ to points $A, B$ and $C$ are $W_A, W_B$ and $W_C$ respectively. Then ( $A, B, C$ are points on semi-circle and point charge $q$ is at the centre of semi-circle)

Two point charges $+6 \mu \mathrm{C}$ and $+10 \mu \mathrm{C}$ kept at certain distance repel each other with a force of 30 N . If each charge is given an additional charge of $-8 \mu \mathrm{C}$, the jwo charges

In a region, the electric field is $30 \hat{\mathbf{i}}+40 \hat{\mathbf{j}} \mathrm{NC}^{-1}$, If the electric potential at the origin is zero. The electric potential at the point ( $1 \mathrm{~m}, 2 \mathrm{~m}$ ) is