Activity 1 — Electric Current
Consider positive and negative charges moving horizontally through the four regions shown in the figure below. Rank the (conventional) current in these four regions from highest to lowest.
Take, as an example, an 18-gauge copper wire (the size usually used for lamp cords), with a diameter of 1.02 mm, that carries a constant current of 1.67 A to a 200-W lamp. The free-electron density in the wire is 8.5 x 1028 per cubic meter. Suppose we replaced the wire with 12-gauge copper wire, which has twice the diameter of 18-gauge wire. If the current remains the same, what effect would this have on the magnitude of the drift velocity vd?
Physics Education Research at UNG 