On an imaginary planet the acceleration due to gravity is same as that on Earth but there is also a downward electric field that is uniform close to the planet's surface. A ball of mass m carrying a charge q is thrown upward at a speed v and hits the ground after an interval t, What is the magnitude of potential difference between the starting point and top point of the trajectory?

Options

A. `(mv)/(2q)(v-("gt")/(2))`
B. `(mv)/(q)(v-("gt")/(2))`
C. `(mv)/(2q)(v-"gt")`
D. `(2mv)/(q)(v-"gt")`