Resistors and Resistance

Resistance, one factor of Ohm’s law,  is the counterpart of the the electrical  current and opposes the current, hence its name. In Ohm’s Law, V=I*R,  the resistance is measured by R=V/I. For example, if the Voltage is 5V and the Current is 20A, the Resistance must be 1/4 ohms. Resistance, which may seem like a bad component of Ohm’s Law, can be very helpful by restricting the flow of electricity and preventing burst light bulbs, LED’s, burnt screens, etc. The amount of resistance can be controlled by a resistor.

Resistors come in  many shapes and sizes, like the small wires and the peanut shaped lump of wood in the center of the light duty resistor or the volume knob on your sound system or radio. Most resistors have insulated paint covering a small copper wiring wrapped tightly around a ceramic rod. These resistors, called wire-wounds, control the resistance by the amount of times the copper wires are wrapped around the rod. The more the turns, the less electricity comes through. Another similar way to make resistors is to replace the copper with a pattern of carbon. The process is cheaper and easier to make in this manner. Consequently, less electricity can be controlled within the resistor.

Resistors have a color coding showing how much the resistor can hold back. There are two sides of the graph, a resistance side and a tolerance side. The resistance side obviously measures the amount the resistor can take on and absorb, and the tolerance side measures the accuracy of the calculated resistance is. An example of such a graph will be shown below.

Resistor color code chart for resistance and tolerance

Resistors and Resistance are both fascinating and complicated subjects in the world of physics and electricity. For more information on Resistors, Resistance, and Ohm’s Law, please click on the following sites below.