Ans: We are given the following:
Current in the wire, 
Distance of a point from the wire, 
Magnitude of the magnetic field at this point could be given as:
![\[\begin{array}{l} \mathrm{B}=\frac{\mu_{0}}{4 \pi} \frac{21}{r} \\ \text { Where, } \mu_{0}=\text { Permeability of free space }=4 \pi \times 10^{-7} \mathrm{~T} \mathrm{~m} \mathrm{~A}^{-1} \\ \Rightarrow \mathrm{B}=\frac{4 \pi \times 10^{-7} \times 2 \times 35}{4 \pi \times 0.2} \\ \Rightarrow \mathrm{B}=3.5 \times 10^{-5} \mathrm{~T} \end{array}\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-6bca16122dfc6df6571db97ac5d002f0_l3.png "Rendered by QuickLaTeX.com")
Hence, the magnitude of the magnetic field at a point 
A long straight wire carries a current of 
