Magnetic Field with three parallel wires

AI Thread Summary
Three parallel wires carrying equal currents experience magnetic forces due to their interactions. Wire B is said to experience the greatest net force because it is influenced by both wires A and C, resulting in a net force of 2I^2/d. In contrast, the forces on wire A and wire C partially cancel each other out, leading to a net force of zero on wire A. The discussion emphasizes understanding the direction of forces based on the nature of the currents, with A and B acting positively and C negatively. Clarifying these interactions is crucial for solving the problem accurately.
rikinmathur
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Homework Statement


Three long, straight wires are carrying currents that have
the same magnitude. In C the current is opposite to that
in A and B. The wires are equally spaced. Each wire experiences a net force due to the other two wires. Which
wire experiences a net force that has the greatest magnitude?

A =====>====
B=====>====
C=====<====

Homework Equations


FAB = μ°I1 I2 / 2∏d

The Attempt at a Solution


It says that the answer is B because 2I squared / d is the net force on B. But the way I am doing it is -I^2/d + I^2/d = 0, hence the net forces cancel out and the force on B is zero. I don't understand how it is 2I^2/d. Please help.
 
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Hi rikinmathur! Welcome to pf! :smile:

What are the direction of forces on wire B due to the other two wires?
 
Hey rikinmathur, just think in terms of charges, maybe this is easier for you: A and B are positively charged (in a magnetic sense) and C is negative. So, which wire-pairs will experience an attractive and which a repulsive force?
 

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