Question

Suppose a straight 2.00 mm -diameter copper wire could just "float" horizontally in air because of the force due to the Earth's magnetic field B⃗ , which is horizontal, perpendicular to the wire, and of magnitude 6.9×10−5 T .


A)What current would the wire carry?

Answer 1

for the magnitude of the force due to the mag field you will need \(F = B \ I \ l\) as the current and field are at right angles.

ie F = Mag field strength * Current * Length.

balance that against gravity, you will need to find the density of copper.