When the charge on an object is doubled, the electric field produced by it becomes:

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

When electric field intensity $\overrightarrow{\mathit{E}}$ at any point in the electric field is directed towards or away from the same fixed point, then the field is

The figure shows electric lines of force in a region. If $E_{\mathrm{A}}$ and $E_{\mathrm{B}}$ are electric fields at points $A$ and $B$ separated by distance $r$, then