Your friend wants to be magician and intends to use Earth’s magnetic field to suspend a current-carrying wire above the stage. He asks you to estimate the minimum current needed to suspend the wire just above Earth’s surface at the equator (where Earth’s magnetic field is horizontal). Assume the wire has a mass of 10 g, and length of 1.0 m. Would you advise him to proceed with his plans for this act?

Under this condition, . In order to suspend the wire, this magnetic force would have to be equal in magnitude to the gravitational force exerted by Earth on the wire the maximum force at angle

F=ILxB

Now to the suspend the wire so use the maximum force and solve to the current knowing the magnetic field of the earth

∑Fy=0

[tex]F_{m}-F_{g}=0[/tex]

[tex]I*L*\beta-m*g=0[/tex]

Solve to I current

[tex]I=\frac{m*g}{L*\beta}[/tex]

[tex]I=\frac{10x10^{-3}kg*9.8m/s^2}{1m*0.5x10{-4}T}[/tex]

[tex]I=1960A[/tex]

I suggest do an toher act is really risk that current for an act