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Homework Statement
There seem to be three right hand rules for dealing with magnetic field, current, and force, and I don't quite understand how to use them.
Namely, I'm having trouble understanding why two parallel wires with current flowing in each of them attract if the currents are in the same direction and repel if they are in opposite directions.
Homework Equations
RHR-1 says that if I "wrap my hand" around the wire where the magnetic field is, my thumb points in the direction of the current. That's all well and good. Both of the wires,next to each other , have current flow upward and, according to RHR-1, a magnetic field "counterclockwise" relative to the current.
The Attempt at a Solution
But I can't figure out how to use the other right hand rule(s) to figure out the direction of each force. The textbook says that the force exerted on the 2nd wire's current I2 by the first wire's current I1 is to the left, and that the force on the 1st wires current I1 by the 2nd wire's current I2 is to the right, making them attract. But how do they know which "direction" the force is going? Is the force centripetal? Or does it go in a definite direction?
I think I might be looking at the problem incorrectly..
Thanks in advance for any help. :)