# Magnetic forces problem

1. Jun 14, 2009

### physics213

1. The problem statement, all variables and given/known data

In the figure below, the current in the long, straight wire is I1 = 4.8 A, and the wire lies in the plane of the rectangular loop, which carries 9.7 A. The dimensions shown are c = 0.10 m, a = 0.15 m, and l = 0.45 m. Find the magnitude and direction of the net force exerted by the magnetic field due to the straight wire on the loop.

2. Relevant equations

F/l = (1.26E-6)(I1)(I2)/(2)(pi)(d)

F= IlBsin(theta)

B=(1.26E-6)(I)/(2)(pi)(r)

3. The attempt at a solution

I figured that we would have to use a combination of the three equations above, and I got an answer of 4.2E-5, but this is incorrect. I believe this answer only takes into account the two wires, not the wire and the rectangle. I am not really sure how to take into account the rectangle. Please help!

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Last edited: Jun 14, 2009
2. Jun 14, 2009

### rl.bhat

Sides of the rectangle parallel to the wire will experience opposite forces. Find the resultant to get the net force.