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Magnetic Field with three parallel wires 
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#1
Dec112, 02:15 AM

P: 1

1. The problem statement, all variables and given/known data
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=====<==== 2. Relevant equations FAB = μ°I1 I2 / 2∏d 3. 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. 


#2
Dec112, 07:19 AM

P: 3,804

Hi rikinmathur! Welcome to pf!
What are the direction of forces on wire B due to the other two wires? 


#3
Dec112, 10:48 AM

P: 11

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 wirepairs will experience an attractive and which a repulsive force?



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