Resistance Measurements

Components are coded by colors to identify their value and function. The colored bands on a resistor allow us to quickly identify a resistor’s value and its percentage tolerance and its physical size indicate its power rating.

Generally, the resistance value, tolerance, and rating are printed on the resistor however, for smaller sized resistors, the specifications are indicated using colored bands. These colored codes can be read off from a color code chart.

Although we can simply measure resistance with an ohmmeter, it is important that we are able to read the color codes to check whether a resistor is faulty. This can be done by looking at the tolerance band indicated on the resistor and comparing it with our meter reading.

Circuit

Resistance can be measured across a resistor using an ohmmeter. In this lab, you will be using a digital multimeter to measure it. The multi-meter passes a current through the resistor and measure the amount of current that went through it. The multi-meter will then display the resistance.

Procedures:

• Read off the nominal resistance of the 4 given resistors from the color code chart.
• Using the tolerance indicated on the resistor, calculate the minimum and maximum resistance
• Measure the resistance of each resistor. Turn the meter on and switch it to the Resistance measurement indicated as Ω. Insert the red probe into the VΩ jack and the black probe into the COM jack of the meter. Initially, the meter should read OL as the resistance of an open circuit is infinity.