# 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 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

• Results about electric charge can be found here.