next up previous contents
Next: Graphite Resistor Up: Lab 2 - Previous: Experiment - DC

Experiment - Resistance Measurement

The standard resistor color code is shown on the back of the door to the lab. Here is a quick synopsis: Most resistors have four colored bands. The first three bands indicate the nominal value of the resistor and the fourth band indicates the tolerance in value. The first two bands form the mantissa, and the third the exponent of 10.

The tolerance band is typically either gold or silver. A gold tolerance band indicates that the measured value will be within 5% of the nominal value. A silver band indicates 10% tolerance. For example a resistor with color code brown-black-red-silver indicates a nominal value of 1 k. The first two bands (brown-black) produce the mantissa (10) and the third band (red) is the exponent of ten (). So the value is . Since the tolerance band is silver, we can expect the measured value of the resistor to be between 900 and 1100 .

  1. Select a 1 resistor (color coded brown-black-red).
  2. Place the resistor in the spring board at your lab station.
  3. Set the multimeter to measure resistance. To do this, press the softkey labeled 2W. Determine the actual value of the resistor. The words ``actual" and ``measured" may be used interchangeably.
  4. Compute the percent difference between the actual (measured) value of the resistor and the nominal value of 1 as indicated by its color code.

You will now create a sequence of carbon resistors. Based on their measured values, you will draw conclusions about the relationship between their physical dimensions and resistance.





cec@ee.duke.edu