# 8. Electric Charges

by M. Bourne

The force between charges is proportional to the product of their charges and inversely proportional to the square of the distance between them.

So we can write:

f(x)=(k\ q_1q_2)/x^2

where q1 and q2 are in coulombs (C), x is in metres, the force is in newtons and k is a constant, k = 9 × 109.

It follows that the work done when electric charges move toward each other (or when they are separated) is given by:

"Work"=int_a^b(k\ q_1q_2)/(x^2)dx

### Example

An electron has a 1.6 × 10^-19\ "C" negative charge. How much work is done in separating two electrons from 1.0\ "pm" to 4.0\ "pm"?

Didn't find what you are looking for on this page? Try search:

### Online Algebra Solver

This algebra solver can solve a wide range of math problems. (Please be patient while it loads.)

Play a math game.

(Well, not really a math game, but each game was made using math...)

Sign up for the free IntMath Newsletter. Get math study tips, information, news and updates each fortnight. Join thousands of satisfied students, teachers and parents!

Given name: * required

Family name:

email: * required

See the Interactive Mathematics spam guarantee.