A particle of mass 2 kg and charge 1mC is projected vertically with a velocity$10{\text{\hspace{0.33em}ms}}^{-1}$. There is a uniform horizontal electric field of${10}^4{\text{\hspace{0.33em}NC}}^{-1}$. [Neglect air resistance, $g=10$${\text{ms}}^{-\text{2}}$]

The horizontal motion is independent of the vertical motion.

Maximum height attained is 5m.

Time of flight is 2s.

Horizontal acceleration is given by ${\mathrm{a}}_{\mathrm{x}}=\frac{\mathrm{qE}}{\mathrm{m}}=\frac{{10}^{-3}\times {10}^4}{2}=5{\mathrm{ms}}^{-2}$

Hence horizontal range is $\mathrm{R}=\frac{1}{2}\times 5\times 2^2=10\mathrm{m}$