Question

State and explain Biot-Savart Law.

Answer 1

The Biot Savart Law is used to determine the magnetic field intensity $B$ near a current carrying conductor in terms of magnetic field intensity generated by its source current element.
Consider a wire carrying an electric current $I$ and also consider an infinitely small length of a wire dl at a distance $r$ from point A.

Biot Savart Law states that magnetic intensity $dB$ at a point A due to current $I$ flowing through a small element dl is
a) Directly proportional to current ($I$)
b) Directly proportional to the length of the element ($dl$)
c) Directly proportional to the sine of angle θ between the direction of current and the line joining the element dl from point A.
d) Inversely proportional to the square of the distance ($x$) of point A from the element $dl$.
$$dB\propto \frac{Idl\sin \theta }{r^2}$$
$$dB=K\frac{Idl\sin \theta }{r^2}$$
where, $K=\frac{{\mu }_0{\mu }_r}{4\pi }$
${\mu }_0=$ Absolute permittivity of air in vacuum
${\mu }_r=$ relative permittivity.