Field around a Conductor
Safety Warnings
Warning: High Current — Low Resistance Circuit
Purpose
Miniature compasses around a vertical current-carrying wire show the circular magnetic field pattern predicted by Ampere's Law. Students observe field direction reversing with current direction (right-hand rule) and field strength increasing with current.
Figure 1:
Projected image of the four compasses before current is applied. All needles point in approximately the same direction, aligned with Earth's magnetic field.
Figure 2:
With current flowing, the compass needles reorient tangentially around the wire, showing the circular magnetic field pattern.
Figure 3:
The conductor table apparatus with vertical copper wire, four miniature compasses, and banana plug terminals for power connections. Designed to sit on an overhead projector.
Figure 4:
Complete setup on the lecture bench: conductor table on the overhead projector, Electro PS-30 DC power supply, and Variac for current control.
Demo Apparatus
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