Resistance is Futile

 

Here is a little information on how the incandescent bulb uses resistance to create light.

 

“One practical and popular use of electric current is for the operation of electric lighting. The simplest form of electric lamp is a tiny metal “filament” inside of a clear glass bulb, which glows white-hot (“incandesces”) with heat energy when sufficient electric current passes through it. Like the battery, it has two conductive connection points, one for electrons to enter and the other for electrons to exit.

 

Connected to a source of voltage, an electric lamp circuit looks something like this:

 

 

As the electrons work their way through the thin metal filament of the lamp, they encounter more opposition to motion than they typically would in a thick piece of wire. This opposition to electric current depends on the type of material, its cross-sectional area, and its temperature. It is technically known as resistance. (It can be said that conductors have low resistance and insulators have very high resistance.) This resistance serves to limit the amount of current through the circuit with a given amount of voltage supplied by the battery, as compared with the “short circuit” where we had nothing but a wire joining one end of the voltage source (battery) to the other.

When electrons move against the opposition of resistance, “friction” is generated. Just like mechanical friction, the friction produced by electrons flowing against a resistance manifests itself in the form of heat. The concentrated resistance of a lamp’s filament results in a relatively large amount of heat energy dissipated at that filament. This heat energy is enough to cause the filament to glow white-hot, producing light, whereas the wires connecting the lamp to the battery (which have much lower resistance) hardly even get warm while conducting the same amount of current.”

 

It is easy to understand why the incandescent bulb is so inefficient when we consider what happens when we turn them on. Electric current is sent through a device meant to inhibit the current’s flow. The device gets so hot it glows. We are producing light (10%) and heat (90%). Not only is that is one process too many, light only makes up 10% of the equation, the rest is waste. Also, we know from our study of the thermal environment that the heat generated by people and machines can effect room temperatures dramatically and increase our relience on HVAC systems. Make light not heat.

 

Another funny thing, why is such an inefficient device used as the icon for good ideas?

 

marcello

 

For the whole lesson on Electric Circuits http://www.faqs.org/docs/electric/DC/DC_1.html

 

“Incandescence – The emission of visible light by a body when heated to a high temperature.” Ching