physics ( need answer very very soon pleaseeeee)
posted by billy on .
An electron enters the region of a uniform electric field between two oppositely
charged parallel plates as shown, with an initial velocity of 3 x 106 m/s. The
electric field between the plates is measured to be E = 200N/C. The horizontal
length of the plates is 10cm.
a. Find the acceleration of the electron while it is in the electric field.
( and if the electron is negativly charged, but we don't know what type it is)

a. Acceleration is
a = e*E/m
e is the electron charge and m is the electron mass
b. Solve the equation
Since the electron's velocity component parallel to the plates remains the same as when it entered,
t = 0.10 m/(3*10^6 m/s) 
how do we find out the electron charge and mass if we don't know what type it is?

sorry but that didn't really give me the answer because we don't know the electron mass or type??