# Definition:Electric Charge

## Definition

**Electric charge** is a physical quantity of matter which causes it to experience a force when near other electrically charged matter.

It is a scalar quantity.

It has been discovered by experiment that the corresponding force depends on the magnitudes of those **electric charges**, their displacements from each other, and their velocities.

### Quantum

**Electric charge** has been demonstrated to be quantized.

The quantum of electric charge is the **elementary charge** $\E$:

- $\E = 1.60217 \, 6634 \times 10^{−19}$ coulombs
*exactly*.

This sequence is A081823 in the On-Line Encyclopedia of Integer Sequences (N. J. A. Sloane (Ed.), 2008).

This is so small that to all practical purposes in everyday measurement of electricity, it can be treated as though it were continuous.

### Symbol

The usual symbol used to denote the **electric charge** on a body is $q$.

### Dimension

The dimension of measurement of **electric charge** is $\mathsf {I T}$.

### Units

The SI unit of **electric charge** is the coulomb $\mathrm C$.

The CGS unit of **electric charge** is the electrostatic unit $\mathrm {e.s.u.}$

## Polarity

The **polarity** of an **electric charge** can be one of $2$ types:

### Positive Electric Charge

A **positive electric charge** is an electric charge which is of the same polarity as the electric charge on a proton.

When it is necessary to assign a value to a **positive electric charge**, a $+$ (plus) sign is used, and the value assigned is a positive number.

### Negative Electric Charge

A **negative electric charge** is an electric charge which is of the same polarity as the electric charge on an electron.

When it is necessary to assign a value to a **negative electric charge**, a $-$ (minus) sign is used, and the value assigned is a negative number.

## Neutral

A body which has no **electric charge** on it is described as **(electrically) neutral**.

## Also see

- Total Force on Point Charge from 2 Point Charges
- Total Force on Point Charge from Multiple Point Charges

- Results about
**electric charge**can be found**here**.

## Sources

- 1921: C.E. Weatherburn:
*Elementary Vector Analysis*... (previous) ... (next): Chapter $\text I$. Addition and Subtraction of Vectors. Centroids: Definitions: $1$. Scalar and vector quantities - 1951: B. Hague:
*An Introduction to Vector Analysis*(5th ed.) ... (previous) ... (next): Chapter $\text I$: Definitions. Elements of Vector Algebra: $1$. Scalar and Vector Quantities - 1960: M.B. Glauert:
*Principles of Dynamics*... (previous) ... (next): Chapter $1$: Vector Algebra: $1.1$ Definition of a Vector - 1976: Ralph J. Smith:
*Circuits, Devices and Systems*(3rd ed.) ... (next): Chapter $1$: Electrical Quantities: Introduction: Forces and Fields - 1976: Ralph J. Smith:
*Circuits, Devices and Systems*(3rd ed.) ... (previous) ... (next): Chapter $1$: Electrical Quantities: Definitions and Laws: Definitions: Table $1$-$2$: Important Derived Quantities - 1990: I.S. Grant and W.R. Phillips:
*Electromagnetism*(2nd ed.) ... (previous) ... (next): Chapter $1$: Force and energy in electrostatics: $1.1$ Electric Charge