Find the value of $\frac{Q_1}{Q_2}$ by looking at the various electric lines of forces between charges $Q_1$ and $Q_2$.

A mass $m=20 \mathrm{g}$has a charge $q=3.0 \mathrm{mC}.$ It moves with a velocity of $20 \mathrm{m} {\mathrm{s}}^{-1}$and enters a region of an electric field $80 \mathrm{N} {\mathrm{C}}^{-1}$in the same direction as the velocity of the mass. The velocity of the mass after $3 \mathrm{s}$ in this region is

Electric field at $O$ along $x-$direction when three point charges $A, B \text{and} C$ with charges $-4q, 2q$ and $-2q$ are present on the circumference of a circle of radius $d$. The charged particles$A, C$ and centre $O$ of the circle formed an equilateral triangle as shown in figure.