how much current to cancel earth's magnetic field?

I don't know the polarity of my magnet. I don't know if it's north, south, or a different one on each side. How do I find out?

A long solenoid (n = 1200turns/m, radius = 2.0 cm) has a current of a 0.30 A in its winding.A long wire carrying a current of 20 A is parallel to and 1.0 cmfrom the axis of the solenoid. What is the magnitude of theresulting magnetic field at a point on the axis of thesolenoid?

If a 190 cm wire carrying 15.00 A of current experiences a force of 0.60N, A)What is the direction and magnetic field intensity that is causing this? B)At what angle would the field need to be at to have the force experienced?

A point charge moving in a magnetic field of 1.24 Tesla experiences a force of 0.81310-11 N. The velocity of the charge is perpendicular to the magnetic field. In this problem, we use the points of the compass and `into' and `out of' to indicate directions with respect to the page. If the magnetic...

My power line from my meter to the electric panel runs in a pvc conduit with several house wires from the old panel box.This was apparently done several years ago during a remodel. Since I have owned this house my electric usage has been 3 times the average for this size home. My question is can...