Suppose you hold a magnetic PHY 221 compass. (A magnetic compass is a magnet that can rotate freely.) The face of the compass is parallel to the tabletop. Predict the orientation of the compass needle when the switch is closed. Sketch a diagram that shows the wire, the direction of the current through it, the direction of the magnetic field Ring St directly below the wire, and the predicted orientation of the compass needle.
Check your answer. If the deflection of the needle is not what you predicted, resolve the discrepancy. (Hint: Is there more than one magnetic field affecting the compass?)
C. Now suppose that you hold the compass at some other locations near the wire (e. g, directly above the wire or to one side of a vertical wire). For each location, predict the orientation of the compass needle when the switch is closed. Make sketches to illustrate your predictions. Check your answers. If the orientation of the compass needle is not what you predicted, resolve the discrepancy
D. Sketch the magnetic field lines of a long, straight current-carrying wire. Include the direction of the current in the wire in your sketch.