# Blog Archives

## Read on. You can’t resist.

This semester I have the pleasure of engaging in a little electrical engineering in my circuits lab. The first area we touched on in here and the first lab revolved around resistors. (Hence the corny title.) Below I have constructed a diagram of the typical two-terminal resistors that we are using and the typical 4 band color coding scheme that they employ.

So take as an example the above resistor diagram. The first step in determining the resistance provided by this particular resistor is to place it in a horizontal orientation as seen above with the metallic-colored band to the right. (In the example, the band is a metallic gold color.) Next you read the bands from left to right like reading this text.

The first band in our example is brown. Using the table, we see brown corresponds to the first digit of the resistance, 1. The second band is black. By the table we see the second digit in the resistance is a zero. The third band which is red tells us what the multiplier is. In this case the multiplier is 100. So with this information we can now calculate the resistance. We multiply the first two digits, 10, times the multiplier, 100, and obtain the resistance in ohms, 1000. Usually this is called 1 kilohm. The final band tells us the tolerance of the resistor. In our example the final band is gold, so the tolerance is +/- 5%. This means that the resistor could have a value from 950 ohms to 1050 ohms.

Besides learning how to determine the resistance we used a digital multimeter to measure the actual value and verify it falls within the range of the tolerance.

Any questions? More to come soon.