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Cake day: August 4th, 2023

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  • If you place a tea bag in a cup of water at 20C in a thermally isolated vacuum chamber, when the chamber pressure is reduced to or below the vapor pressure of water at 20C (about 17 torr, or 1/3 psi), it will begin to boil. The vapor produced will be at 20C and the water in the cup will be 20C and begin to decrease, because of latent heat of vaporization needed for the liquid/gas phase change. The water will continue to boil as long as the pressure is maintained at or below the vapor pressure of water at that temperature. Eventually, the water reaches 0C. Then it will stop boiling and begin to freeze as the latent heat of fusion provides the necessary heat to continue evaporation. When all the water has converted to ice, the vapor pressure is greatly reduced. The ice will sublime (go from solid to gas) still, but as that continues to cool the ice, the vapor pressure also drops. As the temperature drops, sublimation will slow until it is nearly zero. So you would end up with a tea bag encased in ice.

    In your example, if you suddenly exposed to the cup and tea bag to the vacuum of space by rapidly venting the air, the water would explosively evaporate, shredding the tea bag. You’d be left with bits of tea leaves, an empty cup, and a lot of very fine ice crystals.











  • Nothing other than common decency stops a president from executing all rivals of their party, pardoning all those involved, then resigning from the office, turning it over to the VP, before Congress could impeach. Now if the only remaining members of Congress belong to the President’s party, the odds of impeachment diminish significantly. In any case, only one person - the President - could ever be held responsible.

    But anyone dumb enough to try this would start Civil War 2.0.



  • This is the closest to the correct explanation. The reason televisions based on AM radio reception showed static is because of a circuit called the AGC (Automatic Gain Control) which worked like a robotic volume control. Its job is to keep the recovered video signal within a certain amplification range. As long as there was a carrier (the TV station was “on the air”), you’d see whatever the station broadcast. But when they turned off their transmitter, the signal strength would fall and the AGC would increase the amplification until what you see is white noise, mostly due to the random motion of electrons in the electronic components. We can minimize that by cooling, but it can’t be totally eliminated. Audio amplifiers often come with a “hiss” specification that tells you how much of this kind of noise you can expect at normal operating temperature.

    BTW, modern digital TVs -will- show a noise picture if they lack a video muting function when no carrier is detected. I have an LG bought in 2019 that does this, and it’s hella annoying when I accidentally hit the input selection button on the remote, switching from HDMI to TV reception.



  • If your meter can measure AC millivolts, use a shunt. You’ll have to build a special cable from an extension cord. Cut either the live or neutral wire, insert a shunt, which is a resistor with a very low resistance (typically milliohms), then provide some taps at either end of the shunt. Make it all electrically safe. You don’t want to do the 50/60 Hz Shuffle.

    Plug in the extension cord, plug your TV into the extension cord, then measure the AC voltage across the shunt while the TV is operating and apply I=E/R. Now you know the current in the circuit. Measure the wall outlet voltage and use P=IE to determine the power. The measurement is accurate when the power factor of the device being tested is close to 1.

    But honestly, plug-in consumer-level power meters like the Kill-A-Watt are MUCH safer to use, relatively inexpensive, and work for appliances with power factors that are not 1 (like motors). They read out voltage, wattage, and energy usage (KWh).



  • You can subscribe to Easynews. It’s Usenet turned into a website. There’s a built in search engine (supports regular expressions), retention going back to 2008, spam and malware filtering, and multiple servers located in the US and Europe. You choose whether to use the web or a Usenet client. Probably the easiest way to use this neglected corner of the Internet.

    Even Usenet gets censored, but there a window of a couple days between posting and takedown where the file is available. We see this a lot with major studios who pay investigators to identify infringing material. To get around this, some uploaders are encrypting their content, and you’ll need the description key.