Magnetic Force on Current-Carrying Wire Video Lessons

Concept

# Problem: A magnet is hung by a string and then placed near a wire as shown. When the switch is closed, the magnet rotates such that the ends of the magnet move as indicated by the arrows. At the instant the switch is closed determine:Part A. the direction of the current through the wire segment nearest the magnet. Explain. (Hint: Think of the magnet as a compass needle responding to the magnet field that is present.)Part B. the direction of the force exerted by the magnet on the wire segment (assume the magnet is in the position shown). Explain.

###### FREE Expert Solution

Parts A

The current needs to be up since the field of the magnet is going into the south pole.

Suppose I point my right-hand fingers at the magnet, and have the thumb in the upward direction, then my palm will point left. The direction of the push is where my palm points.

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###### Problem Details

A magnet is hung by a string and then placed near a wire as shown. When the switch is closed, the magnet rotates such that the ends of the magnet move as indicated by the arrows.

At the instant the switch is closed determine:

Part A. the direction of the current through the wire segment nearest the magnet. Explain. (Hint: Think of the magnet as a compass needle responding to the magnet field that is present.)

Part B. the direction of the force exerted by the magnet on the wire segment (assume the magnet is in the position shown). Explain.