(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

What is the magnetic field strength and direction at a point 4.0 cm above a wire that carries 12 A of current (the current goes toward the left).

2. Relevant equations

Magnetic field due to a current = {(1.26E-6 Tm/A)(I)(s x r)} / {(4pi)(r^{2})}

Note : s x r is a vector cross product and r here should have a hat over it.

The r in the denominator is just a radius.

3. The attempt at a solution

I am looking at the formula above and I'm not sure what s and r hat are.

Radius I guess would be 4.0 cm, and I think r hat would just be straight down (because doesn't it point from wherever you're calculating the field to the wire?)

But s... I have no idea what that is. Any ideas?

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# Finding the magnetic field due to a current

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