Procedure:

Each lab team will be provided with 3 500 resistors, and a light bulb. A spool of hook-up wire and a spool of nichrome wire will be available to all teams as well. The measuring circuit will consist of a power supply, an ammeter, a voltmeter, and a resistance to be tested called the RUT (resistance under test). The ammeter will be placed in series with the power supply and the RUT so that the ammeter can measure the current $through$ the RUT (and everything in series with it). The voltmeter will be in parallel with the RUT.so that it can measure the potential difference between the terminals of the RUT. The ammeter measures current flow at a point in a circuit. The voltmeter measures the difference in potential between two points points in a circuit. For each RUT, vary the voltage of the power supply and measure $I(V)$. Record the data in a table. The RUT will be in turn a

1. 500 resistor,
2. 3 500 resistors in series,
3. 3 500 resistors in parallel,
4. a light bulb (do NOT crank the voltage past ``7'',
5. a spool of hook-up wire, and
6. a spool of nichrome wire.

Compare the slope of the $I(V)$ graph for the 500 resistor with the value encoded on its body (using the color bands). Compare uncertainty with discrepancy. For the wire in the spools, measure the diameter and estimate the length. From your measurement of the slope of the $I(V)$ graph, estimate the resistivity of the two substances. Compare your results with the expected value for the case of nichrome; for the hook-up wire, guess what the substance might be.