Question

A -6.00 µC charge is moving with a speed of 6.60 104 m/s parallel to a very long, straight wire. The wire is 5.00 cm from the charge and carries a current of 73.0 A in a direction opposite to that of the moving charge. Find the magnitude and direction of the force on the charge.

Answer 1

The force is q V B and is perpendicular to both the wire and the B field, which makes it radial inward. (A negative charge moving opposite to the current direction is attracted to the wire).

For B, use Ampere's law of a straight wire.

B = u * I /(2 pi R)

where u is the permeability of free space, which you will have to look up..

R = 0.05 m

Answer 2

It still says this is not correct. I got 1.156e-4

Answer 3

I get the same number, in units of Newtons.