Question

Question 4.3: A long straight wire in the horizontal plane carries a current of 50 A in north to south direction. Give the magnitude and direction of B at a point 2.5 m east of the wire.

Class 12 - Physics - Moving Charges And Magnetism Moving Charges And Magnetism Page-169

Answer 1

Let us first decide the standard direction on the plane of paper . current carries from North to south direction and point B is placed right side of wire. according to right hand palm rule,
direction of magnetic field is upward . [ see figure]

magnitude of magnetic field ,
$|B|=\frac{\mu_0 2I}{4\pi r}\\\\=10^{-7}\times\frac{2\times50}{2.5}\\\\=4\times10^{-6}T$

hence, in vector form magnetic field $\bf{B}=4\times10^{-6}k\:T$