Question -
Answer -
Charge on a particle ofmass m = − q
Velocity of the particle= vx
Length of the plates = L
Magnitude of the uniformelectric field between the plates = E
Mechanical force, F =Mass (m) × Acceleration (a)
Therefore, acceleration, 
Time taken by the particleto cross the field of length L is given by,
t
In the vertical direction,initial velocity, u = 0
According to the thirdequation of motion, vertical deflection s of the particle canbe obtained as,
Hence, vertical deflectionof the particle at the far edge of the plate is
. This is similar to the motion of horizontalprojectiles under gravity.