Ohm’s law Paul Mac Alevey © Spring 2020 1 Ohm’s law Purpose • To show that the observation called Ohm’s law holds for resistors • To verify formulae for single resistances that are equivalent to resistors in series and in parallel • To examine the effect of ‘grounds’ Equipment  Resistors of approximately 8.2 kΩ, 27 kΩ and 100 kΩ that are attached to dual binding-posts  2 Digital Multi-meters  3 pairs of short banana-to-banana leads (stackable)  1 pair 36 inch banana-to-banana leads (stackable)  DC power supply Verify that you have all of the equipment listed. Notify your TA if anything is missing. Introduction

Ohm’s law Paul Mac Alevey © Spring 2020 2 Resistor Color Codes R Resistors often have four colored bars. The tolerance bar is separated from the others. The resistor should be held so that this bar is at the right. The tolerance bar is gold in the diagram above. The colors of the first three bars on the resistor give the (nominal) resistance of the resistor as follows: Black 0 Brown 1 Red 2 Orange 3 Yellow 4 Green 5 Blue 6 Violet 7 Gray 8 White 9 tens exponent f T units Tolerance bar