Wikipedia:Reference desk/Archives/Science/2019 October 20

= October 20 =

Cells
What elements are cells, for example , the ones in the flesh in our arms , made of ? — Preceding unsigned comment added by 2401:4900:3145:b505:e818:41b4:a5a5:628e (talk • contribs)
 * Do you mean Chemical element in the technical sense, or in the more informal sense of "part"? Either way, Cell (biology) would be a good place to start. Alternatively, this Wikibooks page lists the (chemical) elements in a "typical cell", and their proportions. AndrewWTaylor (talk) 17:35, 20 October 2019 (UTC)
 * We also have Composition of the human body. Someguy1221 (talk) 19:01, 20 October 2019 (UTC)


 * Yes, the cells will be made of the same elements as the parts of the body outside the cells, such as blood plasma and lymphatic fluid, although perhaps at different ratios. SinisterLefty (talk) 01:59, 23 October 2019 (UTC)

Microwaving metal
I've accidentally microwaved forks a bunch of times. No sparks, no explosions, no problems. Why? Temerarius (talk) 15:46, 20 October 2019 (UTC)
 * If you place an antenna into a microwave oven, it will have a voltage and current induced across and along it. That's not necessarily a problem. If it's a fork, then there's really not much which is going to annoy a fork. It also needs to be a big enough fraction of a wavelength to act as a useful antenna - about an inch and a half. There are a few ways to have this go exciting:
 * (the favourite) Place the metal thing so that it passes near the earthed metal case. As it does, there'll be an arc. As this can represent a large current, this is the one which might cause electrical damage to the oven (but modern ovens are designed to be idiot proof).  I've killed the HT diodes in my workshop microwave enough times that there are spares inside the case.
 * Make a loop antenna with a gap in it. This is how Hertz made the very first radio detector. When arranged correctly, this would give a high voltage difference between the two ends, then an arc between them.
 * Use a susceptor, such as the thin tinfoil layer in microwave popcorn bags, but overheat it. This acts as an ohmic heater so unlike the fork, the resistance is high and the current causes the metal to heat up. That might pop your corn, it might set fire to your kitchen. I have a microwave glass kiln - a firebrick  with a conductive lining - which uses this technique to melt glass. Andy Dingley (talk) 19:13, 20 October 2019 (UTC)


 * A CD incorporates a suitably thin metal layer. The most pleasing results are obtained by first dimming the light and using any album by the band Oasis. catslash (talk) 23:33, 20 October 2019 (UTC)
 * Placing a glass with a little water in it in the oven along with the CD will provide the oven with the sort of load that it is designed for. catslash (talk) 23:50, 20 October 2019 (UTC)
 * My lab microwave has among its design specs the minimum amount of various materials (and different values for high-absorbers line methanol and DMSO, medium absorbers like water and acetone, and low absorbers like chloroform and toluene) that gives sufficient total absorbance of the energy to prevent problems. DMacks (talk) 15:22, 22 October 2019 (UTC)


 * AD's answer explains why this is usually not a problem, but I once saw a notice for an old microwave (pre-1990) recommending to put a spoon when heating a cup of liquid (water, coffee, tea...). The likely rationale is to avoid spraying one's face with rapidly-forming steam due to Superheating (I was pleasantly suprised to find that link; most of the time refdesk questions leads to a redlink or a very poor article) . Tigraan Click here to contact me 13:39, 22 October 2019 (UTC)