Resistors are electrical components that we will use quite often. Quite simply they resist the flow of electricity. We will spend more time talking about why we might want to do this in a future lesson. For now we need to focus on how we identify them. It would be convenient if the numerical value was printed on the side of resistors. Unfortunately that's not what they do. Instead, the value of a resistor must be determined using the colored bands that wrap around them. We will focus on four banded resistors, but it should be noted that thereare resistors with more than four bands as well. If you find resistors in older electronic devices they may only have three bands, but this is very uncommon today. The fourth band on almost all resistors made today is gold. If your resistor has gold for the first band simply turn the resistor around so it's the fourth. The fourth band indicates the tolerance. Gold means ±5%. So if the other colors tell us the resistor has a value of 100 ohms, then the true value will lie between 95 and 105 ohms. If the fourth band is silver then it is ±10%. The first band is the first digit in the resistors value. The second band is the second digit. The third band is the multiplier, but I choose to think of this as the number of zeros to tack on.
