The strength of the magnetic field around a long straight wire, carrying current, is

Options

A. inversely proportional to the distance from the wire
B. inversely proportional to the square of the distance from the wire
C. directly proportional to the square of the distance
D. directly proportional to the distance from the wire

Answer

A

Explanation

The magnetic field at a point at a distance r from the long straight wire carryiing current I is given by
`B=(mu_(0))/(4pi)(2I)/(r) or B prop(1)/(r)`