Question

The diagram below represents five different same-length identical wires(red) carrying the same amount of current in the same magnetic field (blue) with current directions and magnetic field directions indicated by arrows.
Which wire(s) experience(s) the most force due to the magnetic field?

• A. 3 only
• B. 2 only
• C. 2 and 5
• D. 1 only
• E. 1 and 4

Answer 1

The correct option is E 1 and 4

The equation for the force on a current-carrying wire in a magnetic field is $F=BIL\sin \theta$, where theta is the angle between the current direction and the direction of the magnetic field.

The more a wire cuts across the field lines, the greater the force. In the equation, the closer theta is to ninety degrees, the greater the force. The closer theta is to zero or one hundred eighty degrees, the closer the force is to zero.

In this case, wires 1 and 4 are at ninety degrees to the magnetic field.