File Name: electric potential and potential difference .zip
Recall that earlier we defined electric field to be a quantity independent of the test charge in a given system, which would nonetheless allow us to calculate the force that would result on an arbitrary test charge. The default assumption in the absence of other information is that the test charge is positive. We briefly defined a field for gravity, but gravity is always attractive, whereas the electric force can be either attractive or repulsive.
Definition : The electrical potential is defined as the capability of the charged body to do work. When the body is charged, either electric electrons are supplied to it, or they are removed from it. In both the cases, the work is done. This work is stored in the body in the form of electric potential. Thus, the body can do the work by exerting a force of attraction or repulsion on the other charged particles. The capacity of the charged body to do work determines the electrical potential on it. The measure of the electrical potential is the work done to charge a body to one coulomb, i.
The electric potential also called the electric field potential , potential drop, the electrostatic potential is the amount of work energy needed to move a unit of electric charge a Coulomb from a reference point to the specific point in an electric field with negligible acceleration of the test charge to avoid producing kinetic energy or radiation by test charge. Typically, the reference point is the Earth or a point at infinity , although any point can be used. More precisely it is the energy per unit charge for a small test charge that does not disturb significantly the field and the charge distribution producing the field under consideration. By dividing out the charge on the particle a quotient is obtained that is a property of the electric field itself. In short, electric potential is the electric potential energy per unit charge.
The electric potential tells you how much potential energy a single point charge at a given location will have. The electric potential at a point is equal to the electric potential energy measured in joules of any charged particle at that location divided by the charge measured in coulombs of the particle. Another way of saying this is that because PE is dependent on q, the q in the above equation will cancel out, so V is not dependent on q. Point charges, such as electrons, are among the fundamental building blocks of matter. Furthermore, spherical charge distributions like on a metal sphere, see figure below create external electric fields exactly like a point charge. The electric potential due to a point charge is, thus, a case we need to consider.
3.2 Electric Potential and Potential Difference
Recall that earlier we defined electric field to be a quantity independent of the test charge in a given system, which would nonetheless allow us to calculate the force that would result on an arbitrary test charge. The default assumption in the absence of other information is that the test charge is positive. We briefly defined a field for gravity, but gravity is always attractive, whereas the electric force can be either attractive or repulsive. Therefore, although potential energy is perfectly adequate in a gravitational system, it is convenient to define a quantity that allows us to calculate the work on a charge independent of the magnitude of the charge. Keep in mind that whenever a voltage is quoted, it is understood to be the potential difference between two points. For example, every battery has two terminals, and its voltage is the potential difference between them. More fundamentally, the point you choose to be zero volts is arbitrary.
Electric potential , the amount of work needed to move a unit charge from a reference point to a specific point against an electric field. Typically, the reference point is Earth , although any point beyond the influence of the electric field charge can be used. The diagram shows the forces acting on a positive charge q located between two plates, A and B, of an electric field E. The potential energy for a positive charge increases when it moves against an electric field and decreases when it moves with the electric field; the opposite is true for a negative charge. Unless the unit charge crosses a changing magnetic field , its potential at any given point does not depend on the path taken.
Electric potential. Exercise: a potential difference of V is applied across a pair of parallel plates m apart. (b) an electron is placed between the plates.
Physics for Computer Science Students pp Cite as. We have seen in the preceding chapter how the presence of an electric charge has an effect on another electric charge. This raises the question: What if there is only one electric charge present? The idea of an electric field is introduced to describe the effect in all space around a charge so that if another charge is present we can predict the effect on it.
Voltage , electric potential difference , electromotive force emf, electric pressure or electric tension is the difference in electric potential between two points, which in a static electric field is defined as the work needed per unit of charge to move a test charge between the two points. In the International System of Units , the derived unit for voltage potential difference is named volt. The old SI definition for volt used power and current ; starting in , the quantum Hall and Josephson effect were used, and recently fundamental physical constants have been introduced for the definition of all SI units and derived units.
The relationship between electric potential and field is similar to that between gravitational potential and field in that the potential is a property of the field describing the action of the field upon an object see. Electric field and potential in one dimension : The presence of an electric field around the static point charge large red dot creates a potential difference, causing the test charge small red dot to experience a force and move. The electric field is like any other vector field—it exerts a force based on a stimulus, and has units of force times inverse stimulus. In the case of an electric field the stimulus is charge, and thus the units are NC In other words, the electric field is a measure of force per unit charge. The electric potential at a point is the quotient of the potential energy of any charged particle at that location divided by the charge of that particle. Its units are JC
The process is analogous to an object being accelerated by a gravitational field. It is as if the charge is going down an electrical hill where its electric potential energy is converted to kinetic energy. This is exactly analogous to the gravitational force in the absence of dissipative forces such as friction. When a force is conservative, it is possible to define a potential energy associated with the force, and it is usually easier to deal with the potential energy because it depends only on position than to calculate the work directly. We use the letters PE to denote electric potential energy, which has units of joules J. PE can be found at any point by taking one point as a reference and calculating the work needed to move a charge to the other point. Gravitational potential energy and electric potential energy are quite analogous.
The basic difference between electric potential and electric potential energy is that Electric potential at a point in an electric field is the amount of work done to bring the unit positive charge from infinity to that point, while electric potential energy is the energy that is needed to move a charge against the electric field. The gravitational potential at a point in the gravitational field is the gravitational potential energy of a unit mass placed at that point. In this way, the electric potential at any point in the electric field is the electric potential energy of a unit positive charge at that point. Electric potential is the scalar quantity. See Also: Types of charges.
Electrical potential difference more important than the actual value of electric potential. The change in potential energy or the work done depends on the size of.