A charged particle (mass m and charge q) moves along X axis with velocity V0. When it passes through the origin it enters a region having uniform electric field. E→=−Ej^ which extends upto x=d. Equation of path  of electron in the region  x>d is

No acceleration in x direction. ​Vx=V0​Time taken to travel distance d = dV0Acceleration in negative y direction = qEm​Magnitude of final velocity in y direction  when it exit the region = Vy=qEm.dV0when x=d, y=−12qEmdv02=y0assume​Now for x>d no acceleration in y direction​y−y0=−Vytx−d=Vxt=V0t​eliminating  t,​⇒-y−y0Vy=x−dV0⇒y=d−xV0Vy+y0=d−xV02.qEdm−qEd22mV02  =qEdmV02d2−x