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Name: Jonathan N.
Status: Other
Age: 40s
Location: N/A
Country: N/A
Date: June 2003

Somebody told me that common light dimmers use as much electrical energy if they are turned up to 100% as they do when they are turned down... to 25% (for instance). Is this true? I do not know too much about electricity, but it seemed to me that it would be more like a water faucet...

They do not use as much energy when turned down. You would know if they did, because the energy that did not go to the light would have to go somewhere, and you could hardly fail to notice it. The dimmer would get hot, for example.

Common light dimmers are more like a pulsating shower head than a faucet. They allow current though for a fraction of each cycle (of 60 Hz), and then they stop the current for the remainder of the cycle.

Tim Mooney

"Old time" dimmer switches were just series resistors that dropped the voltage across a light bulb, but technology has long since replaced these relics. Dimmer switches are really pretty sophisticated now, and a detailed discussion here would not do the topic justice. Better that you look at the interesting web site "How Things Work" for the answer to this and many other "How Things Work" topics:

Vince Calder

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