# Speed of an Electron in an Electric Field

HELLO11

## Homework Statement

Two stationary positive point charges, charge 1 of magnitude 3.25 nC and charge 2 of magnitude 1.55nC , are separated by a distance of 57.0cm . An electron is released from rest at the point midway between the two charges, and it moves along the line connecting the two charges.

find Vfinal of the electron when it is 10.0 cm from charge 1 the want the final answer in m/s

i don't get any of this my professor went to fast. can anyone help?

Staff Emeritus
Homework Helper
This looks like a conservation-of-energy problem.

The two relevant forms of energy are kinetic and electric potential.

HELLO11
do you know of any equations that could help me

Staff Emeritus
Homework Helper
do you know of any equations that could help me

Your book or class notes will have an equation for the electric potential (or voltage) due to a point charge.

To get the net electric potential of the two stationary charges, add up the individual potentials of each of the two charges.

To get the potential energy, multiply electric potential times the charge on the electron. Watch the +/- signs carefully.

HELLO11
can anyone help me

SimonZ
q1 = 3.25 nC, q2 = 1.55nC, d = 0.570 m. charge of electron = q, a = 0.100 m, find the final speed of the electron, v = ?
initial kinetic energy Eki = 0, potential energy Epi = Kqq1/(d/2) + Kqq2/(d/2)
final kinetic energy Ekf = mv^2/2, potential energy Epf = Kqq1/a + Kqq2/(d-a)
energy conservation:
0 + Kqq1/(d/2) + Kqq2/(d/2) = mv^2/2 + Kqq1/a + Kqq2/(d-a)
solve for v.