Register to reply

What makes work positive (electricity)

by Eats Dirt
Tags: potential energy, work done
Share this thread:
Eats Dirt
Feb28-12, 09:02 PM
P: 70
I dont really understand the concept of what makes work positive or negative for example if 3 charges are brought together from infinite what is the work done on them?

I am extremely confused about what make work positive and negative.
Phys.Org News Partner Physics news on
Step lightly: All-optical transistor triggered by single photon promises advances in quantum applications
The unifying framework of symmetry reveals properties of a broad range of physical systems
What time is it in the universe?
Feb29-12, 05:20 AM
Sci Advisor
HW Helper
tiny-tim's Avatar
P: 26,148
Hi Eats Dirt!

Potential energy = minus the work done by a conservative force.

And work done = force "dot" displacement
so if the charge is attractive (like gravity), the force is in the same direction as displacement, so the work done by the force is positive, and the potential energy difference is negative

but if the charge is repulsive, the force is in the opposite direction to displacement, so the work done by the force is negative, and the potential energy difference is positive

Register to reply

Related Discussions
The angle that A makes with the positive x axis Introductory Physics Homework 3
Find the magnitude and the angle that it makes with the positive x-axis? Calculus & Beyond Homework 1
The conservation of energy, why does it work? Negative work vs positive work Introductory Physics Homework 54
What makes a matrix positive ? Precalculus Mathematics Homework 4
Positive electricity? Classical Physics 2