An experiment on the earth's magnetic field (5.5 10-5 t) is being carried out 4.8 m from an electric cable. what is the maximum allowable current in the cable if the experiment is to be accurate to 1.0% ?

13.2 A

Explanation:

Earth's magnetic field B= 5.5×10^{-5} T

the distance r= 4.8 m

the permeability of free space μ_o=

according to Biot Savart law

therefore, current in the table is

solving we get I= 1320 A

if the experiment is to be accurate to 1.0%

then the allowed value of current in the cable

I'= I(1%)

=

= 13.2 A

-4 on

that would be because of both gravity and friction. so     c