Question

State Biot-Savart law.

Answer 1

Bio Savart Law: The magnetic field at any point due to an element of a conductor carrying current is
(1) directly proportional to (a) the strength of the current $i$,
(b) length of the element $dl$ (c) sine of the angle $\theta$ between the element in the direction of current and the line joining the element to the point P.
i.e., $dB\propto i,dB\propto \delta ,dB\propto sin\theta$
(2) inversely proportional to the square of the distance r of the point P from the centre of the element.
$dB=\frac{{\mu }_0}{4\pi }\times \frac{Idlsin\theta }{r^2}$