Electric Potential Energy Concept

[r0306]

I'm unsure if the following is true or not in the absence of external forces:

• Electric potential is a scalar quantity.

This I know is true because there is no direction associated with potential energy.

• It is always possible to assign a value of zero to the electric potential at the origin.

This I am completely unsure of though I think it is true because potential depends on a reference point that you can set yourself.

• The change in a particle's potential energy depends on the total length of its path between two points.

I suspect that this is true because U = qV and V is dependent on the distance between the points.

• The work required to move a charge q from a point at potential Vi to a point at potential Vf is q(Vf - Vi).

This should be false because (delta)U = q(Vf - Vi) and W = -(delta)U so it should be -q(Vf - Vi) instead.

Can someone please verify my reasoning and correct me if I'm wrong? Thank you.

 

[TESL@]

q(Vf - Vi) is correct for the work done by the force opposing the electric force. If the work done by electric field was being considered, it would be q(Vi - Vf).

 

[r0306]

q(Vf - Vi) is correct for the work done by the force opposing the electric force. If the work done by electric field was being considered, it would be q(Vi - Vf).

That means all of the points listed are true then? I'm really uncertain about the second point.

 

[TESL@]

Your second point is true as long as you offset the potentials of all the charges in the system wrt. the ground you take.

 

[ninipanini]

what did u end up getting for this?