22.3 Biot Savart or Laplace's Law
Figure 4
Consider a small element PQ of a conductor through which current i flows. Let d
l be the length of the element. Let A be any point at distance r from the center of the element.
Let the line joining the center 'O' to A make
Ðq with PQ.
Then, the intensity of the magnetic field at A due to current i in the element PQ is found (by
experiments) to be (in magnitude) proportional to i, d
l, sin q , .
The direction of is given by Ampere's rule, which is
perpendicular^{ }to the plane in the diagram
and pointing into the plane.
In vector form, equation (1) can be represented as,
Note: Biot Savart Law is applicable only if the current
is a steady current. This is possible only in closed loops or infinite
conductors.
