A body having specific charge 8   μC   g - 1 is resting on a frictionless plane at a distance…

A body having specific charge $8 \mathrm{\mu C} {\mathrm{g}}^{-1}$ is resting on a frictionless plane at a distance $10 \mathrm{cm}$ from the wall (as shown in the figure). It starts moving towards the wall when a uniform electric field of $100 \mathrm{V} {\mathrm{m}}^{-1}$ is applied horizontally towards the wall. If the collision of the body with the wall is perfectly elastic, then the time period of the motion will be $\_\_\_\_\mathrm{s}.$