# Calculating vertical displacement of an electron (millikan's experiment)

1. Oct 25, 2004

### KWL

this one question has got me confused...any help/hint would be appreciated.

an electron is travelling horizantally at a speed of 8.7*10^6 m/s enters an electric field of 1.32*10^3 N/C between two horizantal plates (shown below)
+ ___________________

e- ---->

- ___________________

The horizantal plates are each 14.0 cm and are distanced 8 cm from each other.

I need to calculate the vertical displacement of the electron as it travels between the plates.

2. Oct 25, 2004

### Tide

The electron is accelerated at a constant rate by the electric field. It's a simple matter to find its trajectory - mass times acceleration = charge times e-field.

3. Oct 26, 2004

### niehls

if it helps, think of it as a regular projectile trajectory with the only force acting on the electron being vertical.The horizontal component of the speed stays the same, and it's accelerated towards the positively charged plate. the acceleration is given by newton's second law according to Tide's post.