An electron falls through a distance of \(1.5~\text{cm}\) in a uniform electric field of magnitude \(2\times10^4~\text{N/C}\) [figure (a)]. The direction of the field is reversed keeping its magnitude unchanged and a proton falls through the same distance [figure (b)]. If \(t_e\) and \(t_p\) are the time of fall for electron and proton respectively, then:

   
1. \(t_e=t_p\)
2. \(t_e>t_p\)
3. \(t_e<t_p\)
4. none of these$\mathrm{}$

Two-point charges $q_1$ and $q_2$, of magnitude $+{10}^{-8}<mspace\; width="1em"></mspace>C$  and $-{10}^{-8}<mspace\; width="1em"></mspace>C$, respectively, are placed 0.1 m apart. The electric field at point  A (as shown in the figure) is: 

$1.<mspace\; width="1em"></mspace>3.6\times {10}^4<mspace\; width="1em"></mspace>{\mathrm{NC}}^{-1}$
$2.<mspace\; width="1em"></mspace>7.2\times {10}^4<mspace\; width="1em"></mspace>{\mathrm{NC}}^{-1}$
$3.<mspace\; width="1em"></mspace>9\times {10}^3<mspace\; width="1em"></mspace>{\mathrm{NC}}^{-1}$
$4.<mspace\; width="1em"></mspace>3.2\times {10}^4<mspace\; width="1em"></mspace>{\mathrm{NC}}^{-1}$