Question

State Biot Savart law. 

Answer 1

The magnetic induction, according to Biot Savart law, at a point P at a distance r due to current element Idl is given by

`"d"vec"B" = μ_0/(4π) . ("I"dl sin "θ")/r^2` inward as shown

In the vector form, it can be written as

`vec"dB" = (μ_0 "I")/(4π) . ( bar(dl) xx hatr )/r^2` , θ is the angle `bar(dl)` vector and `hatr` is the position vector of the point P.

Clearly, dB ∝ I
                  ∝ dl
                  ∝ `l/r^2`
                  ∝ sin θ
μ₀ is the absolute permeability of free space.