Magnetic Moment, PLEASE ANSWER quick

AI Thread Summary
To determine the direction of the magnetic moment of the upper wire, the right-hand rule can be applied to the current direction. The magnetic field from the lower wire points out of the page, and the force acting on the upper wire is directed to the right. To find the torque, the cross-product of the magnetic moment and the magnetic field is used, indicating a counterclockwise rotation. The discussion also emphasizes calculating the force per unit length on the upper wire and how it affects the total torque. Understanding these principles will clarify the rotational direction of the wire.
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So here are two wires. With currents in the specified direction.

What I want to know, is how do you determine the direction of the magnetic moment of the upper wire, which would ultimately lead to me determining what direction its torque is in, therefore letting me determine what direction it rotates in (the answer is CCW, I do not know how to get it though).

I know that the B-field on it from the second wire, points out of the page.
And I know that the Force acting on it (due to the lower wire), is to the right.

Cross-Product Rules:
τ = μ x B
τ = F x r

I know when the current is in a loop, to find μ direction you just wrap your hand around, and your thumb points in the direction. But this wire is just a wire... I have no clue how to use a right-hand rule on the current alone.
 
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letsgo said:
I know that the B-field on it from the second wire, points out of the page.
And I know that the Force acting on it (due to the lower wire), is to the right.

That's right. What's the magnitude of the force above P compared to the magnitude of the force below P? Which way will I2 rotate (I assume P is a pivot).

What's the force per unit length at each point on I2? How would you compute the total torque given this force per unit length?
 
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