A long wire is known to have a radius greater than 5.6 mm and to carry a current that is uniformly distributed over its cross section. The magnitude of the magnetic field due to that current is 0.44 mT at a point 4.0 mm from the axis of the wire, and 0.27 mT at a point 32 mm from the axis of the wire. What is the radius of the wire?

The radius is

Explanation:

Generally Magnetic field due to a current  carrying wire is is mathematically represented as

Where is the distance from the axis of the wire to the first  point we are considering

            I is the current

              is the permeability of free space

Making I the subject

Generally Magnetic field inside a  current  carrying wire is is mathematically represented as

Now the r here is the distance from the axis of the wire to the second point we are considering

And R i the radius of the wire  

           Making R the subject of the formula

Substituting for I we have

Where B = 0.27mT

And     = 0.44mT

             r = 32mm

              = 4.0mm

Substituting values

explanation:

newton's third law, for every action there is an equal and opposite reaction.

the displacement produced by the body.  

the amount of force subjected to the body.  

the angle between the direction of force and displacement