| Objective: |
| To find the important relationship between the current
and the integral of the magnetic field around a closed loop containing
the wire. |
| Steps: |
 |
From the previous page we know the connection between
magnetic flux density and current. For a circular loop, we find
that the integral of the flux density equals a constant times
the current. |
| |
|
 |
The definition of Ampère's Law is the line
integral of the magnetic field around a single closed loop is
equal to the total current enclosed. |
| |
|
 |
It does not matter if the wire is not in the centre
of the closed loop. The loop need not be circular - it must, however,
enclose the wire only once.
If there is more than one wire, the integral gives the sum of
the currents enclosed (taking into account the current direction). |
| |
|
 |
Shows some examples of currents linked with curves. |