Electric charge
Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.
Description
There are two types of electric charges: positive and negative. Like charges repel and unlike attract. An object is negatively charged if it has an excess of electrons, and is otherwise positively charged or uncharged. The SI derived unit of electric charge is the coulomb (C).
In electrical engineering, it is also common to use the ampere-hour (Ah), and, in chemistry, it is common to use the elementary charge (e) as a unit. The symbol Q often denotes charge.
Early knowledge of how charged substances interact is now called classical electrodynamics, and is still accurate for problems that don't require consideration of quantum effects.
The electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction.
Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force, which is one of the four fundamental forces (See also: magnetic field).
Twentieth-century experiments demonstrated that electric charge is quantized; that is, it comes in integer multiples of individual small units called the elementary charge, e, approximately equal to 1.602×10−19 coulombs (except for particles called quarks, which have charges that are integer multiples of 1/3 e).
The proton has a charge of +e, and the electron has a charge of −e. The study of charged particles, and how their interactions are mediated by photons, is called quantum electrodynamics.
See also
- Current 3-vector
- Direct current
- Electric shock
- Electrical measurements
- History of electrical engineering
- Hydraulic analogy
- International System of Quantities
- SI electromagnetism units
- Single-phase electric power
- Three-phase electric power
- Two-phase electric power
External links
- Electric charge @ Wikipedia.org
