This is the basis for Coulomb's law, which states that, for stationary charges, the electric field varies with the source charge and varies inversely with the square of the distance from the source. The electric field acts between two charges similarly to the way the gravitational field acts between two masses, as they both obey an inverse-square law with distance. : 469–70 Fields that may be defined in this manner are sometimes referred to as force fields. having both magnitude and direction), it follows that an electric field is a vector field. : 469–70 As the electric field is defined in terms of force, and force is a vector (i.e.
The electric field is defined at each point in space as the force per unit charge that would be experienced by a vanishingly small positive test charge if held stationary at that point. The field is depicted by electric field lines, lines which follow the direction of the electric field in space. Įlectric field of a positive point electric charge suspended over an infinite sheet of conducting material. The derived SI unit for the electric field is the volt per meter (V/m), which is equal to the newton per coulomb (N/C). The electric field is defined as a vector field that associates to each point in space the (electrostatic or Coulomb) force per unit of charge exerted on an infinitesimal positive test charge at rest at that point. It is also the force responsible for chemical bonding between atoms that result in molecules. In atomic physics and chemistry, for instance, the electric field is the attractive force holding the atomic nucleus and electrons together in atoms. Electric fields and magnetic fields are both manifestations of the electromagnetic field, one of the four fundamental interactions (also called forces) of nature.Įlectric fields are important in many areas of physics, and are exploited in electrical technology. Electric fields originate from electric charges and time-varying electric currents. It also refers to the physical field for a system of charged particles. The electric field strength is equal to negative the potential gradient.An electric field (sometimes E-field ) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. The potential gradient in an electric field is defined as the change in potential per unit distance in a given direction. In a radial field, these are circular lines with increasing separation as the distance away from the centre increases. For a uniform field, the equipotentials are equally spaced lines between the plates. For a uniform field, a straight line is formed as the electric field strength is constant.Įquipotentials are points of equal potential within a field.
The gradient of the graph at a point is the electric field strength.
UNIFORM ELECTRIC FIELD FREE
The unit of $E$ is the newton per coulomb ($NC^$ is the permittivity of free space and $r$ is the separation between the centres of the charge.Ī graph of the electric potential against distance from the charge can be plotted. The electric field strength, $E$, at a point in a field is defined as the force per unit charge exerted on a positive test charge placed at that point. The stronger the field, the greater the number of field lines per unit area. In a radial field, the field lines point either towards or away from the centre of charge. The field lines that make up a electric field can take several shapes:įor a uniform field, the field lines are parallel to each other, at right angles to the plates and acting from the positive plate to the negative plate. The direction of the field lines depend on the shape of the objects. The path a small positive charge would take in an electric field is called the field line. Electric charge $Q$, is measured in coulombs ($C$), and can either be positive or negative.