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Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. Even the filament from an incandescent light bulb is effectively a resistor, slowing down the current and heating up a wire to a high enough temperature that it gives off light. This light given off is known as blackbody radiation. Resistors also have applications in electrical devices like computers and cell phones to damp out unwanted electrical signals.
It's counter-intuitive, but even though energy is dissipated with resistance, resistors are absolutely essential to the proper functioning of electronics. They function to ensure that other components aren't provided with too much voltage or electric current.
For more detailed information on resistors please see hyperphysics. An explanation of the colour code seen in figure 1 can be found here. There are numerous different ways to build a resistor, and each method has benefits and drawbacks in terms of versatility and cost. The two major types of resistors that can be seen are variable and fixed resistors.
Variable resistors, shown in Figure 2, are simply a special type of resistor that can be adjusted to any ohmic value - or level of resistance - within a certain range. These resistors are the most common type of resistor and are built to resist at a specific ohmic value - meaning simply that they have one associated, pre-determined resistance value.
The resistor will feel cool to warm by touch. The relatively low temperature is a result of the resistor acting as a semiconductor, meaning that it is allowing only a specific amount of current to flow through. Current is the flow of electrons. When electrons meet resistance, as they do in a semiconductive material, they produce heat. Resistors are designed to dissipate the heat so the semiconductive material is not damaged.
When a resistor is placed under a voltage that approaches the upper limits of its power rating, the resistor generates more heat than normal. This is due to the voltage attempting to force more current electrons through the resistor than it is designed to pass.
The resistor will be hot to touch and a faint whiff of burning may be detectable. The burning odor is the breaking down of the components of the resistor: the carbon, the clay binding agent and the color code pigment painted on the resistor.
When a resistor has been overloaded with voltage exceeding its power rating, the resistor will become very hot to touch, darken considerably and possibly even melt or catch on fire. Although a resistor may appear damaged at this point, it can still be functioning. However, it may be functioning with less resistance than it was originally designed for.
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