1. Electrical Potential Electrical Potential Energy Electrical Potential
Equipotential Surfaces
Potential Due to an Electrical Field
Potential Due to a Point Charge
Potential Due to an Electric Dipole
Potential Due to a Continuous Charge
Calculating the Field from Potential
Potential of Point Charge
Potential of an Isolated Charged Conductor
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2. When an electrostatic force exists between two or more charged particles in a system of particles, one can assign an electric potential energy to that system of particles. The amount of work needed to move the particles from an infinite distance to their positions is equal to the potential energy of the system. The potential energy depends on the magnitude of the charge.
The potential energy per unit charge has a unique value measured in Joules per Coulomb. This value is called the electric potential, V. One volt is equal to one Joule per Coulomb.
Electric potential is a property of an electric field, regardless of whether a charged object has been placed in that field, measured in volts. Electric potential energy is the energy of a charged object in an external electric field. The work done to move the charged object into the field is the charge multiplied by the change in electric potential.
Adjacent points which have the same electric potential form an equipotential surface. This may be an actual surface or an imaginary one.
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3. The electric potential between two points can be calculated from the work done in moving the charge into its position.
Using this information and substituting r for s, the electric potential can be calculated. A positively charged particle produces a positive electric potential. A negatively charged particle produces a negative electric potential.
If one has a group of electric charges, one only has to sum the electric potential from al of the objects.
If one has an electric dipole, the electric potential can be determined using the dipole moment.
Many molecules have permanent dipole moments. Since electrons are capable of moving, a molecule placed in an electric field, the electrons can move creating an induced dipole moment.
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4. When a charge distribution is continuous such as on a thin rod or wire, the potential at a distance, r, from the line of charge.
If a charge is distributed over a circular disk, one can determine the potential along the z axis through the center of the disk.
The component of the electric field in any direction is the negative rate of change of electric potential with respect to the distance.
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5. The electric potential energy of a system of fixed point charges is equal to the work that must be done by an external agent to assemble the system, bringing each charge from an infinite distance.
An excess of electric charge placed on an isolated conductor will distribute itself on the surface of the conductor so that all points on the conductor, whether on the surface or inside, will come to the same potential. This is true even if the conductor has an internal cavity and even if the cavity contains a net charge.
On a non-spherical surface the charge does not distribute the itself uniformly over the surface of the conductor. At sharp point or edges, the charge density and the electric field can reach very high values. The air nearby may become ionized and produce a coronal discharge which could be a precursor to sparks or lightning.
Enclosing an object inside a conducting shell will protect the object from the electric field.
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