Final answer:
The potential energy of a charge in an electric field changes as the charge moves through a potential difference. The work done on the charge by the electric field is the change in potential energy. The kinetic energy of a charged particle can be calculated from the work done on it by the electric force.
Step-by-step explanation:
The potential energy of a charge in an electric field represents the energy it has due to its position within the field. If a charge moves between two points with a potential difference, there is a change in potential energy. According to the work-energy principle, the work done by the charge in moving through this potential difference is equal to the change in potential energy. (a) When a charge moves through a potential difference, the work done on the charge is the product of the charge (Q) and the potential difference (V), expressed as W = QV. This work done is also the change in potential energy of the system. (b) The kinetic energy of a charged particle at a point in an electric field can be determined by considering the work done by the electric force on the particle. If the particle starts from rest, all the work done on the charged particle by the electric field will be converted into its kinetic energy (assuming no other forces are doing work).For a pair of charges or a system of charges, the potential energy is the sum of the potential energies resulting from each pair of charges within the system. If the charges are moved closer or farther apart, the potential energy changes, which may result in work done on or by the system, depending on the force required to move the charges and the direction of the movement.