Although the evidence is weak, there has been concern in recent years over possible health effects from the magnetic fields generated by transmission lines. A typical high-voltage transmission line is 20 m off the ground and carries a current of 200 A.

A. Estimate the magnetic field strength on the ground underneath such a line.
B. What percentage of the earth’s magnetic field does this represent?

A

The magnetic field strength on the ground underneath such a line is

B

The percentage of the earth’s magnetic field does this represent is 4%

Explanation:

 Mathematically the magnetic field can be expressed as follows

 Where is the permeability of free space

           I is the current

            R is the distance

   Generally the magnetic field at the Earth surface is

Hence the percentage of the earth field it represents is

                                %

i believe it is b. what was the cause of the big bang

hope this !