Question

The force on a wire is a maximum of 5.20 N when placed between the pole faces of a magnet. The current flows horizontally to the right and the magnetic field is vertical.

The wire is observed to "jump" toward the observer when the current is turned on. If the pole faces have a diameter of 14.0 cm, estimate the current in the wire if the field is 0.112 T.

If the wire is tipped so that it now makes an angle of 13.4° with the horizontal, what force will it now feel?

Answer 1

Find the current from the length of wire in field:

F = ILB

Substitute given values

5.20 N = I (0.14 m) (0.112 T)

Solve for current I

I = 331.6 A

Round off the result to 3 significant digits

I = 332 A

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In this situation, the new force is

  F_new = I L B sinθ

= F sinθ

      = (5.20 N) sin( 90 -13.4 )°

= 5.06 N