Magnetic field at a distance r from an infinitely long straight conductor carrying a steady current varies as

Options

A. `(1)/(r^(2))`
B. `(1)/(r)`
C. `(1)/(r^(3))`
D. `(1)/(sqrtr)`

Answer

B

Explanation

Magnetic field due to an infinitely long straight conductor carrying steady current at a distance r from it is given by `B = (mu_(0) 2 I)/(4 pi r) or B prop (1)/(r)`