This paper will give you a better understanding of resistors and what they are. They are used all around us in our day to day lives in the electrical world. They are used in every house, automobile, school and piece of equipment that has electricity.
Resistors are electrical devices that have specific electrical resistance and used if a voltage drop is needed. There are four different factors that determine resistance. Different materials have different amounts of electrons, which increase or decrease resistance. Naturally the length of a material adds resistance. The cross sectional area or thickness. The fatter a wire, the less resistance it has than a thinner wire of the same material. And last, most materials have resistance that change with temperature. .
Resisters are either wire wound or carbon-composition. A wire-wound resistor is exactly that. It is wires that are wrapped around creating a longer path for electricity and slowing it down. They are used when the drop needs to be 5 watts or more. .
Carbon-composition resistors are found in electronic devises that use low wattage. The are made in 1/8-W, 1/4-W, 1/2-W, 1-W, and 2-W sizes. They are marked with a color code placed on the resistor. The color code reveals their ohmic value. The color code is as follows: 0- Black, 1- Brown, 2- Red, 3- Orange, 4- Yellow, 5- Green, 6- Blue, .
7- Violet, 8- Gray, 9-White. When reading this, the resistor should be held so that the bands are on the left side and read from left to right. The first band gives the first number, the second band the second number, and the third band, the multiplier or divisor. The third band states the number of zeros to add to the first two bands. For example if you have a resistor with the colors red, violet, orange, and silver the rating would be 27000ohms. If there is no fourth band, the resistor has a tolerance of plus or minus 20%. If the fourth band is silver, the resistor has a tolerance of plus or minus 10%.