# Using e in a Formula

#### hardwork

When using e (for electron) in a formula, do you use +1.6x10^-19 C or -1.6x10^-19 C?

For example:

http://i44.tinypic.com/25g9te8.jpg

An electron moved from c to a. How much work is done by the electric force?

Electric Potential
Point a = 6.2x10^5 V
Point c = -7.5x10^4 V

Work = (-1.6x10^-19 C) (Va - Vc) = -1.1x10^-13
-W(electric force) = +1.1 x 10^-13

OR

Work = (1.6x10^-19 C) (Va - Vc) = 1.1x10^-13
-W(electric force) = -1.1 x 10^-13

Related Introductory Physics Homework Help News on Phys.org

#### LowlyPion

Homework Helper
Welcome to PF.

Electron carries a negative charge.

#### rl.bhat

Homework Helper
According to the definition of the potential difference between the two points, it is the work done on the positive charge to move it against the electric force.
So the magnitude of the work is the same. Only difference is whether it is on the charge or by the charge.

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving