What is ampere’s law?
According to this law “The line integral of magnetic field B along a closed path due to current is equal to the product of the permeability of free space and the current enclosed by the closed path”.
Mathematically it is expressed as:
μ0=permeability of free space
i=current flowing through the conductor.
Consider a straight conductor in which current i is flowing.The current produces the magnetic field B around the conductor.The magnetic field lines are in the form of concentric circles.
Where is the length of the path called circumference of the circle.
Divide the circle representing the magnetic field line into large number of small elements each of length dl.The quantity B.dl is calculated for each element as:
For complete circle:
Integral form of ampere law:
Differential form of ampere law:
Since the integral form of ampere’s law is:
The above relation is known as differential form of ampere’s circuital law.