Technology Digging - TD1.us

Most of the commercial resistors come with the power rating in watts and resistance value. Highest voltage rating is another important parameter. Suppose if the rating of the resistor is 150 Watts and 10 Ohm, then it means that the resistor will work normally up to the 150 Watts energy dissipation at the resistor.

For simplicity, suppose the resistor of 10 Ohm is connected to a battery of 12V supply. There is no other component, then the current flowing through the resistor is 1.2 Amp. (R=V/I). Now if you want to calculate the how much energy is dissipated and whether the resistor will work normally, then you must calculate the power dissipated using the formulae (E=V*I, E=I^2*R, or E=V^2/R). Now in this case the energy dissipated is 14.4 Watts which is lesser than the wattage rating of resistor, i.e., 150 Watts and therefore the resistor will work normally in this environment.

Choosing the right wattage and value resistor for a particular application in the electronic circuit is very important and you can use this method to calculate the power dissipation in the resistor. Most commonly used resistors have the following wattage: 1/8W, 1/4W, 1/2W, 1W, 2W, 3W, 5W and 10W.

There are many interesting facts about resistor value, wattage and the configuration of the resistors. Suppose there is one 6 Ohm resistor with 1/2 Watt and if you want to reduce the wattage to 1/8 Watt, then you can use resistors in series like 2 Ohm resistors in series (3 resistors) with wattage lesser than 1/2 Watt will work in this case.

Tags: Electronics