Electricity is a phenomenon arising from the movement or accumulation of electric charges, fundamental properties of matter carried by elementary particles. The electron is the particle involved, carrying a negative charge. Electricity manifests through the motion and interaction of these electrons, whether stationary (static electricity) or moving (electric current). Electric current, the flow of electric charge, is driven by voltage, the difference in electric potential. Electricity and magnetism are two aspects of electromagnetism .

What is an electric current?

Electric current is the movement of electric charge carriers, which can be subatomic particles such as electrons or ions. In a wire, electric current measures the amount of charge passing a certain point in the wire per unit of time. Electric current flows through electric circuits and is driven by a difference in electric potential, known as voltage. Depending on its direction, current can be direct (DC), where the flow of electrons is unidirectional, or alternating (AC), where the flow reverses periodically. The common unit for measuring electric current is the ampere , equivalent to one coulomb of charge per second. Electric current generates a magnetic field, and when it flows in an external magnetic field, it experiences a magnetic force.

How does electricity flow in a circuit?

Electricity in a circuit involves the movement of negatively charged electrons through a conductor, like a wire. This movement is driven by a voltage , or difference in electric potential, across the conductor. The flow of current follows a path called an electric circuit , which needs a power source and a device that uses electricity. Depending on the direction of flow, current can be direct (DC), flowing in one direction, or alternating (AC), periodically reversing direction. Circuits can be arranged in series, where components are along one path, or parallel, where each operates independently. In series, one component failure disrupts the entire circuit, while in parallel, the others can still function.

What are conductors and insulators in electricity?

In electricity, materials are categorized as either conductors or insulators based on their ability to allow electric current to flow. Conductors Materials like metals (e.g., copper) have free electrons that can move easily, allowing them to conduct electricity efficiently. When a voltage is applied, these electrons flow, creating an electric current. Insulators Materials like plastics and ceramics have electrons tightly bound in ionic or covalent bonds, restricting their movement. As a result, they resist the flow of electric current. The difference in electrical properties arises from how atoms bond together. Metals have metallic bonds where electrons float loosely, whereas insulators have electrons locked in place.

How do voltage, current, and resistance relate to each other?

Ohm's law describes the relationship between voltage, current, and resistance in an electrical circuit. Voltage is the electric potential difference that causes the flow of charge, measured in volts. Current is the flow of electric charge, measured in amperes. It is directly proportional to voltage and inversely proportional to resistance. Resistance opposes the flow of current, measured in ohms. It is the ratio of voltage to current. Ohm's law is expressed as (V = IR), where (V) is the voltage, (I) is the current, and (R) is the resistance. This means that at a constant resistance, current increases as voltage increases. With a constant voltage, increasing the resistance decreases the current.

What are some common uses of electricity in everyday life?

Everyday life relies on electricity for various purposes. Electricity is the movement of negative charges carried by electrons . Common applications include:

electricity

Introduction
Electrostatics
- Coulomb’s law
  - Calculating the value of an electric field
  - Superposition principle
  - Electric potential
  - Deriving electric field from potential
- Capacitance
  - Principle of the capacitor
  - Dielectrics, polarization, and electric dipole moment
  - Capacitors in series and parallel
  - Applications of capacitors
Direct electric current
- Basic phenomena and principles
- Conductors, insulators, and semiconductors
- Electromotive force
- Direct-current circuits
- Resistors in series and parallel
- Kirchhoff’s laws of electric circuits
Alternating electric currents
- Basic phenomena and principles
- Transient response
- Alternating-current circuits
  - Behaviour of an AC circuit
  - Resonance
Electric properties of matter
- Piezoelectricity
- Electro-optic phenomena
- Thermoelectricity
- Thermionic emission
- Secondary electron emission
- Photoelectric conductivity
- Electroluminescence
- Bioelectric effects

References & Edit History Related Topics

Images & Videos

A graph with x and y axes shows two points labeled Q1 and Q2 representing electric charges. A dashed line labeled r connects the charges, with arrows indicating the electric force F acting on Q1 and negative F acting on Q2.

A diagram showing the electric force vector F between two charges, with its x and y components represented by dashed arrows. The x component points right and is labeled Fx = 3.6 times 3/5 newtons; the y component points downward and is labeled Fy = -3.6 times 4/5 newtons. The force vector F has a magnitude of 3.6 newtons and points diagonally down and right from the origin.

A coordinate plane diagram shows three point charges: Q1 at (0.04, 0), Q2 at (0, 0.03), and Q3 at (-0.03, 0). Blue arrows at Q1 indicate the electric field vectors E1,2 and E1,3, and their total E1, all pointing away from Q1 at different angles.

A diagram shows a positive charge labeled Q on the left and two dashed paths from point B to point A on the right. Path 1 goes directly from B to A, while path 2 follows a route from B to C to D to A. Both paths illustrate possible ways to move a second charge q in the presence of Q.

A 3D plot shows two potential energy surfaces: section A, shaded red, rises sharply to illustrate the repulsive potential between two positive charges; section B, shaded blue, dips downward to show the attractive potential between a negative and a positive charge.

Diagram of an electrode configuration inside a metal tube, showing a blue circular rod at -20 volts and a red L-shaped bracket at +20 volts, with the tube itself at zero volts.

A grid of numbers on a gray background represents electrostatic potentials in volts. Central rows show red numbers at 20 volts and blue numbers at negative 20 volts, with other values decreasing outward and zeros along the edges.

A diagram of equipotential surfaces shows contour lines labeled with voltages from plus 20 volts near a red L-shaped object to minus 20 volts around a blue circle, illustrating how electric potential changes in space.

Diagram showing electric field lines as dashed curves radiating from a blue circle and bending around a red L-shaped object, with denser lines indicating stronger electric fields.

At a Glance

electricity summary

electricity

physics

Written by

Frank Neville H. RobinsonAll

Fact-checked by

Britannica Editors

Last updated

Oct. 18, 2026 •History

Electrostatics

Electrostatics is the study of electromagnetic phenomena that occur when there are no moving charges—i.e., after a static equilibrium has been established. Charges reach their equilibrium positions rapidly because the electric force is extremely strong. The mathematical methods of electrostatics make it possible to calculate the distributions of the electric field and of the electric potential from a known configuration of charges, conductors, and insulators. Conversely, given a set of conductors with known potentials, it is possible to calculate electric fields in regions between the conductors and to determine the charge distribution on the surface of the conductors. The electric energy of a set of charges at rest can be viewed from the standpoint of the work required to assemble the charges; alternatively, the energy also can be considered to reside in the electric field produced by this assembly of charges. Finally, energy can be stored in a capacitor; the energy required to charge such a device is stored in it as electrostatic energy of the electric field.

Coulomb’s law

Static electricity is a familiar electric phenomenon in which charged particles are transferred from one body to another. For example, if two objects are rubbed together, especially if the objects are insulators and the surrounding air is dry, the objects acquire equal and opposite charges and an attractive force develops between them. The object that loses electrons becomes positively charged, and the other becomes negatively charged. The force is simply the attraction between charges of opposite sign. The properties of this force were described above; they are incorporated in the mathematical relationship known as Coulomb’s law. The electric force on a charge Q₁ under these conditions, due to a charge Q₂ at a distance r, is given by Coulomb’s law, Equation.

The bold characters in the equation indicate the vector nature of the force, and the unit vector r̂ is a vector that has a size of one and that points from charge Q₂ to charge Q₁. The proportionality constant k equals 10⁻⁷c², where c is the speed of light in a vacuum; k has the numerical value of 8.99 × 10⁹ newtons-square metre per coulomb squared (Nm²/C²). Figure 1 shows the force on Q₁ due to Q₂. A numerical example will help to illustrate this force. Both Q₁ and Q₂ are chosen arbitrarily to be positive charges, each with a magnitude of 10⁻⁶ coulomb. The charge Q₁ is located at coordinates x, y, z with values of 0.03, 0, 0, respectively, while Q₂ has coordinates 0, 0.04, 0. All coordinates are given in metres. Thus, the distance between Q₁ and Q₂ is 0.05 metre.

The magnitude of the force F on charge Q₁ as calculated using equation (1) is 3.6 newtons; its direction is shown in Figure 1. The force on Q₂ due to Q₁ is −F, which also has a magnitude of 3.6 newtons; its direction, however, is opposite to that of F. The force F can be expressed in terms of its components along the x and y axes, since the force vector lies in the xy plane. This is done with elementary trigonometry from the geometry of Figure 1, and the results are shown in Figure 2. Thus, Equation. in newtons. Coulomb’s law describes mathematically the properties of the electric force between charges at rest. If the charges have opposite signs, the force would be attractive; the attraction would be indicated in equation (1) by the negative coefficient of the unit vector r̂. Thus, the electric force on Q₁ would have a direction opposite to the unit vector r̂ and would point from Q₁ to Q₂. In Cartesian coordinates, this would result in a change of the signs of both the x and y components of the force in equation (2).

battery. Illustration of battery connected to lightbulb. Power a light bulb with a battery. Battery, Power Supply, Science, Circuit, Currents

Britannica Quiz

Electricity: Short Circuits & Direct Currents

How can this electric force on Q₁ be understood? Fundamentally, the force is due to the presence of an electric field at the position of Q₁. The field is caused by the second charge Q₂ and has a magnitude proportional to the size of Q₂. In interacting with this field, the first charge some distance away is either attracted to or repelled from the second charge, depending on the sign of the first charge.

electricity

Electrostatics

Coulomb’s law

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