# Homework Help: Electrical field

1. Apr 6, 2004

### UrbanXrisis

An electron is accelerated from rest for a time of 10R-9 seconds by a uniform electrical field that exerts a force of 8E-15 N on the electron. What is the magnitude of the electrical field?

What equations should I use? There's E=F/q and E=kQ/r^2 They both dont work.

The speed id the electron after it has accelerated for 10E-9 seconds is most nearly? How do i calculate this?

2. Apr 7, 2004

### jamesrc

Why doesn't E=F/q work?

As far as the speed goes, it's a particle moving with constant acceleration. The fact that it's an electron doesn't really have anything to do with anything at this point. You've got a particle of mass m (if you can't remember the mass of an electron, you should be able to look it up quickly), accelerated by a force F. That means its acceleration is a = F/m. If you want to find velocity given a constant acceleration and the time of the acceleration, you just use v = v(0) + a*t (here v(0) is given as 0).