Compute the magnetic of the magnetic field of a long, straight wire carrying a current of 1 A at distance of 1m from it. Compare it with Earth's magnetic field .

Explanation

Given that I = l A and radius r = l m
`B_("straightwire") = (mu_(0)l)/(2pi r) = (4 pi xx 10^(-7) xx l)/(2 pi xx l ) = 2 xx 10^(-7) `T
but the Earth.s magnetic field is `B_("Earth") ~ 10^(-5)` T
So, `B_("straightwire")` is one hundred times smaller than `B_("earth")`.