Activity 3 — Resistivity and Resistance
Three wires are made of copper having circular cross sections. Wire 1 has a length L and radius r. Wire 2 has a length L and radius 2r. Wire 3 has a length 2L and radius 3r. Which wire has the smallest resistance?
A metal wire of resistance R is cut into three equal pieces that are then placed together side by side to form a new cable with a length equal to one-third the original length. What is the resistance of this new cable?
When does an incandescent light bulb carry more current? Is it just after you flip the switch and turn on the light? Or is it after the light has been on for a little while?
Physics Education Research at UNG 