Part B: Ammeters, Voltmeters, and Ohm's Law

Set up circuit depicted below, to measure the current flowing through a resistor and the voltage across the resistor. We will use a power supply capable of a variable voltage to alter the current flow.

Our object is to do measurements of current (I) and voltage (V) to check Ohm's Law for a resistance (R) V = IR.

Obtain a resistor from the instructor and the meters.

Vary the voltage of the power supply and make a table showing the results of the current and voltage measurements. Plot the current as a function of the voltage, and deduce the value of the resistance from the slope of the curve. Compare this value of $R$ from the value one gets from the color code, and the colored bands on the resistor. Is the discrepancy within the uncertainty of the value or $R$ read off of the resistor?

Note that Ohm's law is a simple proportionality or linear law. Since current is directly proportional to the voltage, one can simply measure the voltage, multiply by the appropriate conversion factor, and calculate the current flowing through the resistor. Since voltages are so easy to measure, this is often the easiest way of measuring current! (But, only for ``Ohmic'' circuit elements).