Potential Energy and Electric Potential
One idea wearing two costumes, side by side: a ball lifted through height contours, and a charge moved through equipotential rings. Drag either one and change how big it is — the stored energies scale, but gh and V do not. Place 1 C, 2 C and 3 C at the same point and U/q comes out identical every time.
Cara memakai simulasi ini
- Drag the ball across the height contours and the charge across the equipotential rings
- Press 1 kg / 1 C, 2 kg / 2 C or 3 kg / 3 C to change the object at the same place
- Press Try all three here to put all three charges at one point and compare U/q
- Press Reset to return both pictures to their starting positions
Yang perlu diamati
- Trebling the charge trebles the stored energy at the same point
- U/q is the same for all three charges, because potential does not depend on what you bring
- Moving along one contour or equipotential ring changes no energy at all
- The gravitational and electric pictures behave identically under every change
- Potential describes the position; potential energy describes the object in that position
Fisika di baliknya
Energy stored depends on the object as well as the place: U = mgh for the ball and U = qV for the charge. Dividing that energy by the property that made it large removes the object from the answer, leaving gh and V — quantities belonging to the field and the position alone. Electric potential is defined exactly this way, V = U/q, which is why a point in a field has one potential no matter what charge you bring to it, or whether you bring any at all.