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The long, thin wire shown in the figure is in a region of constant magnetic fiel

ID: 1694408 • Letter: T

Question

The long, thin wire shown in the figure is in a region of constant magnetic field . The wire carries a current of 6.2 A and is oriented at an angle of 7.5 degrees to the direction of the magnetic field.
http://session.masteringphysics.com/problemAsset/1122622/1/Walker.22.28.jpg

A.) If the magnetic force exerted on this wire per meter is 3.4×10-2 N, what is the magnitude of the magnetic field? I got 58 mT and then 51 mT. Both were wrong.
B.) At what angle will the force exerted on the wire per meter be equal to 1.4×10-2 N?

Explanation / Answer

current through the wire   I = 6.2 A angle    ? = 7.5 ^ o magnetic force on the wire due to magnetic field           F = I B L sin ?           F / L   = I B sin 7.5             3.4*10^ -2 = 6.2 * B sin 7.5       magnitude of magnetic field                   B = 4*10^ -2 T b)    1.4 *10^ -2   = ( 6.2 ) ( 4*10^ -2 ) sin ?               sin ?   = 0.056                     ?   = 3.23 degrees