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location New York, United States
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visits member for 4 years, 7 months
seen Jun 22 at 4:04

I am an electrical engineer who is easily distracted by physics.


Jun
22
revised Would wearing clothing that is black on the inside and white on the outside keep you cooler?
add source
May
24
awarded  Popular Question
May
11
comment Is there a limit to the resolving power of a mirror telescope?
or shaping the mirror with a magnetic field
May
11
revised Would wearing clothing that is black on the inside and white on the outside keep you cooler?
added 434 characters in body
May
2
comment Are small speakers inherently limited to higher frequencies?
Crude illustration: flic.kr/p/spT8rC flic.kr/p/s8tspQ
May
2
comment Are small speakers inherently limited to higher frequencies?
The speakers will all be close together in a single enclosure, and it's a subwoofer, not full-range, so I don't think there will be any more diffraction than that produced by the surface of a large cone. 200 Hz wavelength is 4.4 times the diameter of the cone, 20 Hz wavelength is 45 times.
Apr
28
comment Are small speakers inherently limited to higher frequencies?
"When you try to combine a bunch of small surfaces in different locations to recreate a single wave you end up with a some random interference where the wave is stronger or weaker" I don't understand how a bunch of cones near each other moving in phase with each other at low frequencies would be different from a single large cone. Isn't the main problem that small drivers don't have as much excursion?
Apr
26
comment Is there a limit to the resolving power of a mirror telescope?
"no known technologies to manufacture such a big mirror with the required precision" How about en.wikipedia.org/wiki/Liquid_mirror_space_telescope?
Apr
9
comment Choosing sign for KVL (mutual inductance)
OK I understand, thanks
Apr
9
comment Choosing sign for KVL (mutual inductance)
I mean diagram 2 of 3, where the currents are both flowing inward. They aren't meant to indicate the flow of current? I2 has a negative value, so is actually flowing outward?
Apr
9
comment Choosing sign for KVL (mutual inductance)
I don't understand the second diagram. Energy would be flowing into both the primary and secondary, no?
Dec
30
comment How can you focus sound?
@pete: I don't know about focusing on a point smaller than the wavelength. As for changing the shape of the waveform (which would be nonlinear distortion), it would not happen at low amplitudes, since air pressure waveforms just add together linearly. But I believe it is intentionally distorted at high amplitudes in the "audio spotlights", using the high pressure at the focal point combined with the nonlinearity of the air to demodulate ultrasound into audible frequencies.
Dec
2
awarded  Benefactor
Dec
2
comment Why does only one side of a neon lamp glow?
Combining you answer with sh37211's, it seems the electrons are accelerated toward the anode, where they have sufficient energy to ionize gas atoms, and then the gas ions are accelerated toward the cathode, until they gain enough energy to excite neutral gas atoms in collisions, and those neutral gas atoms relaxing to non-excited state is what emits most of the light, so the ions being faster at the cathode end is why there is more light there? Maybe the spectrum varies from end to end because the neutral atoms are excited to different states?
Dec
2
comment Does (will) wind affect plasma (electical spark passing through a gap)?
It's more similar to fire than to light. :)
Dec
2
comment Are the ions in a fluorescent lamps concentrated near the electrodes?
"Fluorescent lamps may get dim at one end with DC. Since the mercury vapor ionizes more easily than the argon, some of it exists as positive ions. This can cause the mercury to be pulled to the negative end of the tube, resulting in a mercury shortage at the positive end. This is more of a problem with longer length and smaller diameter tubes. ... Some ... have special switches to reverse polarity every time the fixture is started. This balances electrode wear and reduces mercury distribution problems." repairfaq.org/sam/dlamp.htm
Dec
1
revised Why does only one side of a neon lamp glow?
some typos, etc
Dec
1
revised Why does only one side of a neon lamp glow?
added 91 characters in body
Dec
1
suggested approved edit on Why does only one side of a neon lamp glow?
Dec
1
comment Why does only one side of a neon lamp glow?
Can you summarize your reference instead of just linking? Your reference says "A neon display lamp uses the positive column for its light", which would seem to mean the positive end glows, which is not the case in reality.