# Ampere's Law

Written by Jerry Ratzlaff on . Posted in Electromagnetism

Ampere's Law (Maxwell's fourth equation) states:

• A flowing electric current (J) gives rise to a magnetic field that circles the current
• A time changing electric flux density (D) gives rise to a magnetic field that circles the D field

## Ampere's Law formula

$$\bigtriangledown \;x\; H = \frac { \partial D} { \partial t} + J$$

Where:

$$\bigtriangledown \;x\;$$ = divergence operator

$$D$$ = electric displacement

$$H$$ = magnetic field strength

$$J$$ = electric current density

$$t$$ = time