# Fundamental Physics/Electromagnetism/Electric charge

## Electric charge

 Electric charge Charge process Charge quantity Electric field Magnetic field Negative charge O + e -> - - Q -->E<-- B ↓ Positive charge O - e -> + + Q <--E--> B ↑

## Electric charge interaction

### Coulomb law

Like charges repel, different charges attract . Negative charge attracts positive charge . The force of attraction negative charge attracts positive charge is called Electrostatic force can be calculated by Coulomb law as follow

${\displaystyle F_{Q}=K{\frac {Q_{+}Q_{-}}{r^{2}}}}$

### Ampere law

The force that sets electric charge in motion from stationary state is called Electromotive force can be calculated by Ampere law as follow

${\displaystyle F_{Q}=QE}$

### Lorentz law

When electric charge interacts with magnetic field of a magnet, the magnetic force of the magnet will make electric charge to move perpendicular to the initial moving direction . The positive charge will move up, the negative charge will move down . The force of magnetic field that sets electric charge to move perpendicular to the intial moving direction is called Electromagnetomotive force can be calculated as follow

${\displaystyle F_{B}=\pm QvB}$

The sum of 2 forces Electromotive force and Electromagnetomotive force creates Electromagnetic force

${\displaystyle F_{EB}=F_{E}+F_{B}=QE\pm QvB=Q(E\pm vB)}$

## Electric charge interaction force

 Electrostatic force ${\displaystyle F_{q}=K{\frac {q_{+}q_{-}}{d^{2}}}}$ Electromotive force ${\displaystyle F_{E}=qE}$ Electromagnetomotive force ${\displaystyle F_{B}=\pm qvB}$ Electromagnetic force ${\displaystyle F_{EB}=F_{E}+F_{B}=qE\pm qvB=q(E\pm B)}$

## Application

The force of attraction of 2 different charges

${\displaystyle F=K{\frac {Q_{-}Q_{+}}{r^{2}}}=K{\frac {Q^{2}}{r^{2}}}}$ . ${\displaystyle Q_{-}=Q+}$

The electric field of the charge in motion

${\displaystyle E={\frac {F}{Q}}={\frac {Q}{r^{2}}}}$

The potential of the electric field

${\displaystyle V=\int Edr={\frac {Q}{r}}}$