Question

The magnetic flux density B at a distance r from a long
straight wire carrying a steady current varies with r as

Answer 1

Answer:

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Answer 2

Answer:

Magnetic flux density,B for a stright conductor is inversely proportional to  the distance,r .

Explanation:

The magnetic flux density B at a distance r from a long straight wire carrying a steady current (I) varies with r is given by  

                    $B = \frac{\mu_0I}{2 \pi r}$  

                  ∴  $B \propto \frac{1}{r}$

Therefore , magnetic flux density,B for a stright conductor is inversely proportional to the distance,r .

Additional Information:

From Ampere's circuital law,we can write that

     $\int \vec{B} . \vec{dl} = \mu_0 I_{enclosed}$

 →  $B = \frac{\mu_0I}{2 \pi r}$