# Homework Help: Simple Magnetism Question

1. Sep 2, 2004

### Del

" A 1.5-m length of wire carrying 6.5 A of current is oriented horizontally. At that point on the Earth's surface, the dip angle of the Earth's magnetic field makes an angle of 40 degrees to the wire. Estimate the magnetic force on the wire due to the Earth's magnetic field of 5.5*10^-5 T at this point."
I'm sure it's very easy but this is the first day I've worked with this stuff so I can't figure out why I'm getting it wrong. I used the equation F=ILBsinθ so; F=(6.5A)(1.5m)(5.5*10^-5)sin40, which gives F=3.45*10^-4. However I checked and the correct answer is, F=2.9*10^-4. Please someone tell me what I'm doing wrong. Thanks in advance.

2. Sep 3, 2004

### jamesrc

Um, I think you're right. Either that or we've both made the same mistake. How confident are you that the "correct" answer is correct?

3. Sep 5, 2004

### Del

Boy is it a pain to get wrong correct answers. I now feel dumb for trying so hard to get the stupid thing "right"

-Del