Calculating Electron Velocity with 3eV Energy

[brad sue]

Homework Statement

Calculate the velocity of an electron with 3 eV energy. This electron is accelerated by a constant field of 10 V/cm (parallel to the electron velocity) for 0.1 cm. What is the new electron velocity?

My other problem is the unit for the electric field . it bothers me: V/cm usually it is N/C

Homework Equations

.5*m*v^2

Please can i have some suggestions?

The Attempt at a Solution

3eV=3 x 1.6E-19=4.8E-19 joules=1/2 mv^2, so v^2=4.8E-19/4.5E-31=1E12
so v=10^6 metres/sec.

 

[kuruman]

You should be aware of the fact that 1 V/m = 1 N/C. So 1 V/cm is how many N/C?

 

[brad sue]

100 N/C
thank i forgot all those units!

to find the final speed, i use the formula (Vfinal)^2-(Vinitial)^2=2a*(0.1 e-2)
when i did I found Vfinal =1.03 e6 m/s

the velocity difference i think is very small , it seems not right. did i do the question corretly?
thank you