So, recently while I was studying electric fields and charges for a test, I came across the definition of electric potential as –
The amount of work done in moving a unit positive test charge from infinity to a point, without changing its kinetic energy, i.e, without acceleration against the force due to an electrostatic field.
But this contradicts to what the work-energy theorem says, that the work done equals the change in kinetic energy. What am I missing here?
Also, what exactly is electric potential? Why can we only define a potential for a conservative field?
Best Answer
If you were using the work energy theorem then you would need to consider both the forces on the charge which are the external force and the force due to the electric field.
These two forces are equal in magnitude and opposite in direction so the net force on the charge is zero.
So the net work done on the charge is zero which leads to the conclusion that the change in the kinetic energy of the charge is zero.
What you are missing from your definition are the words done by an external force.
ie that definition only includes one of the two forces acting on the charge.