Earth's magnetic field at New York City?

Question

At New York City, the earth's magnetic field has a vertical component of 5.2 x 10^-5 T that points downward (perpendicular to the ground) and a horizontal component of 1.8 x 10-5 T that points toward geographic north (parallel to the ground). What is the magnitude and direction of the magnetic force on a 25.0 m long, straight wire that carries a current of 31 A perpendicularly out of the ground?

Answer 1

The magnitude of the magnetic field is:

B = (Bx² + By²)^(1/2) = ((1.8 x 10^-5)² + (5.2 x 10^-5)²)

= 5.5 x 10^-5 T

The force on the wire:

F = ILB = 31 A x 25 m x (5.5 x 10^-5 T)

= 0.043 N upwards

Hopefully I did that correctly.