Light Dimmers and Resonance Name: Edward M. We have several
incandescent bulbs that are controlled by dimmers. If the
dimmers are slowly moved, there are several positions where the
bulb makes a noise. I assume these noises represent some sort of
resonant frequency, but what is vibrating? and what property of
the changing electrical energy is altering the vibration to set
up the resonance? Am I correct in assuming that to maximize bulb
life the dimmer should be set to avoid these noises? Interesting
question. Possible sources might be: 1. A "hum" from the dimmer
-- presumebaly a transformer -- due to the 60 hertz AC current.
This is the very familiar hum you pick up around unshielded AC
circuits. 2. The AC current might set up a vibration in the
filament, or its wire leads. This would be a much higher
frequency pitch. If it is the latter, certainly you would want
to avoid those settings. I do not know, but I would guess the
dimmer decreases the portion of the normal sine wave which will
be let through to the