The Biot-Savart Law relates magnetic fields to the currents which are their sources. In a similar manner, Coulomb’s law relates electric fields to the point charges which are their sources. Finding the magnetic field resulting from a current distribution involves the vector product, and is inherently a calculus problem when the distance from the current to the field point is continuously changing.
Consider a conductor through which a current I flows and let small elemental length dl at a source point. We want to calculate magnetic field at a point which is distance r from source point. θ be the angle between r and dl. Then from biot-savart law the magnetic field due to current carrying conductor is
directly proportional to the magnitude of current,
directly proportional to the length of element dl