Answer:
a
The current that would be produced is
b
Yes this arrangement can be used to cancel out earths magnetic field at points well above the Earth's surface.This is because this current loop acts as a magnetic dipole for point above the earth surface
c
No this arrangement can not be used to cancel out earths magnetic field at points on the Earth's surface .this because on the earth surface it shifts from its behavior as a magnetic dipole
Explanation:
From the question we are told that
The magnetic moment of earth is
The radius of earth generally has a value of
Magnetic moment is mathematically given as
A is the area of the of the earth(assumption that the earth is circular ) and this evaluated as
Now making the subject in the above formula