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warfreak131
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Homework Statement
Hey all, I am studying for the GRE and I need help with this question:
A rectangular loop of wire with dimensions shown above (see attachment) is coplanar with a long wire carrying current I. The distance between the wire and the left side of the loop is r. The loop is pulled to the right as indicated.
What are the directions of the induced current in the loop and the magnetic forces on the left and the right sides of the loop as the loop is pulled?
Induced Current ... Force on Left Side ... Force on Right SideA. Counterclockwise ... To the left ... To the right
B. Counterclockwise ... To the left ... To the left
C. Counterclockwise ... To the right ... To the left
D. Clockwise ... To the right ... To the left
E. Clockwise ... To the left ... To the right
The Attempt at a Solution
Currently, the magnetic field from the current wire is moving into the page along the right side. As the loop is pulled away, it attempts to maintain the magnetic field. This means that the induced magnetic field along both sides of the loop are of the same orientation as before.
The left side of the loop experiences a greater magnetic force than the left side, meaning the current would travel clockwise.
If you look at the magnetic force, F=q(VxB), and calculate the force for a positive charge, the left side force would be to the left, and the right side force to the right. Since electrons are negative and travel in opposition to current, v becomes -v, and q becomes -q. This double negative cancels out, though.
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