4 ms·

The pdf claims that for simplicity sake, the constant pi should have been a factor of two larger. Reminds me of electrical engineering "mistakes" such as the c

• amalcon 16y ago
  I was about to write something very similar. There have always been a small number of people who claim that electromagnetic charges should be reversed: that is, that the positively charged particle should logically be what "moves" in the circuit. Most people just look at it, shrug, decide it doesn't really matter, and get back to doing it the way they've always done.
  • teilo 16y ago
    The small minority of people may have a point, but it's the wrong point, since the real problem with the notation of electric charge has nothing to do with the formulas which are used, but with the connotation that people give them of somehow representing a surplus or deficit of electrons, neither of which is true. The only real relationship between the charges is that they are opposite. The terms positive and negative have no other meaning. As for the formulas, either way will work just fine, as long as everyone is consistent. Pick something and stick with it.
    • Benjo 16y ago
      Are you saying people confuse charged ions with flowing current in a circuit? My view of the problem is that it's hard to grasp what current actually is. The water in a pipe analogy works, but it's confusing because the electrons flow in the opposite direction of the hcurrent, making the "water" positively charged electron holes.
      • sid0 16y ago
        > Are you saying people confuse charged ions with flowing current in a circuit? Charged ions moving in an electrolytic cell is charge flowing in a circuit. Electrons are not the only way to have a current.
      • teilo 16y ago
        That's the thing. When we are talking about current, we are not talking about how many electrons are moving, but about the transfer of energy from one place to another. The water analogy just doesn't work, because while the current itself flows at nearly the speed of light, the electrons themselves move very slowly. In an AC current, the electrons don't flow at all. They vibrate. And in a liquid, the energy transfer can just as well be by means of anion flowing backwards, as cations flowing forward. Yet we think of the current as only flowing in one direction. You see the problem? Trying to think of electrical energy as a "flow of electrons" OR a "flow of protons" completely skews one's understanding of what is taking place.
    • sesqu 16y ago
      somehow representing a surplus or deficit of electrons, neither of which is true. If an electric charge of -4e doesn't represent a surplus of 4 electrons, what does it represent? Surely not a deficit of 4 protons, since they are much harder to move around? Perhaps you feel it represents a transient property of matter that just so happens to be closely related to, but not defined by, the movement of elementary particles? That's a reasonable position to take, if you don't have to effect a charge.
  • Tiomaidh 16y ago
    And that electrical engineers tell you that current goes from + to -, while physicists say it goes from - to +. And the north magnetic pole is at the geographic south / vice versa. And horsepower != 1000 Watts. And Farads are bigger than I'd like them to be.
• anigbrowl 16y ago
  He has a point. I've always found the diameter:circumference ratio so much more natural for thinking about geometry that when I used to program regularly I had a macro called 'tupi' which would expand to (2 * pi) at compile time. Whatever mental blind spot I have about it was causing me to introduce a bug about a quarter of the time I needed to reference pi, probably because some part of my brain was continually asking what point there was to a constant that needed doubling in order to be useful.
  • jerf 16y ago
    I just starting futzing around with a project using OpenGL and literally just last night wrote myself up a pi2 constant after the third time I found myself writing 2*pi. And three's the charm for refactoring.
  • ez77 16y ago
    But diameter:circumference :: 1:pi, not 1:2pi. Do you mean radius:circumference?
    • anigbrowl 16y ago
      Quite - making this sort of mistake repetitively was why I made a substitute. It's like a word I mispronounce every. damn. time. :-)
• tbrownaw 16y ago
  Whole amps and handfuls of ohms aren't that rare, they actually match pretty well to what comes out of the wall socket. And that 1.8v or 0.85v or whatever it is these days space heater that runs your computer takes really quite a lot of amps.
  • ori_b 16y ago
    On the other hand, Farads or Teslas...
    • amalcon 16y ago
      Coulombs are my favorite, because it's the fundamental amount of "something" (as opposed to "something per time") that most of these can be traced back to: Ampere = Coulomb/second Farad = Coulomb/volt
  • Benjo 16y ago
    Yes, but >=kiloamps and <=milliohms are that rare, which makes it seem like the whole scale is off by a factor of 1000 or so.
  • sliverstorm 16y ago
    Frankly, I have always appreciated that Ohms are almost never partial. milliohms are a rare occurrence, and I just think that's great and works out well, IMHO. Amps being too large is unfortunate, but it's not a big deal.