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The known causes of electricity (2019)

15 points by jimhi 5y ago

wishawa 5y ago
This is wrong. Light CAN cause electricity. See the Photoelectric effect (https://en.wikipedia.org/wiki/Photoelectric_effect https://en.wikipedia.org/wiki/Photoelectric_effect).
- yetihehe 5y ago
  Yeah, there are many wrong and some disinformed statements in that article: > The most popular batteries use chemicals to store the energy. And then when we want to use the energy, we simply draw it back out. This is pretty much how the electrical grid works. No, electrical grid currently mostly works without batteries. Power stored in batteries which can give it back to grid is several orders of magnitude smaller than what grid transfers. But this may change in future. > Also, electricity can cause pressure (well can make things expand) [...] I could not find any current use cases for this property, I will have to look further. Ultrasonic scanners in doctors offices or ultrasonic motors for some camera lenses, or even those sound-playing birthday cards. > One you’ve seen a million times in the bath, but you never noticed. When bubbles pop, they can cause a small amount of light. This is called Sonoluminescence. They cause a really really small amount of light lasting a few hundred trillionths of a second. Yeah, but that's not electricity.
  - jimhi 5y ago
    > Ultrasonic scanners in doctors offices or ultrasonic motors for some camera lenses, or even those sound-playing birthday cards. I am confused by your statement on this one. Birthday cards use tiny batteries. > Yeah, but that's not electricity. Perhaps the science was updated on this, but articles like this say they can get up to 1W out of it. https://physicsworld.com/a/brightest-bubble-bursting-yet/ https://physicsworld.com/a/brightest-bubble-bursting-yet/
    - yetihehe 5y ago
      > Birthday cards use tiny batteries. And piezoelectric buzzers https://en.wikipedia.org/wiki/Buzzer https://en.wikipedia.org/wiki/Buzzer > but articles like this say they can get up to 1W out of it Yeah, but they are getting electricity from light, sonoluminescence generates light, not electricity and author even singled out light as being something different than electricity, you can have light from electricity according to him.
      - jimhi 5y ago
        Interesting, thanks. Is there anything you know of that does the opposite? Uses pressure to generate electricity?
        yetihehe 4y ago
        Piezoelectric crystals. Change in pressure causes electricity flow. They are used in piezoelectric lighters and in some microphones. Buzzers from birthday cards can work both ways, as a microphone (pressure->electricity) and as a speaker (electricity->pressure).
jleyank 5y ago
I naively thought that “electricity” is electrons moving from point a to point b under some potential (ie, a current). The electrons have to be able to move, which might be small in a conductor or higher in an insulator. And the photoelectric effect appears when photons of the appropriate energy blow electrons from the bound to the unbound state. Can’t say I recall a course that discussed the causes of electricity, so there must be a jargon problem here, I thought lightening came when the charge separation (or magnitude?) at the top of the cloud exceeded any insulation effect of the air. But then uni was a while ago. Fried various low voltage devices with static charges though, and I thought that was lightening writ small.

15 points by jimhi 5y ago

This is wrong. Light CAN cause electricity. See the Photoelectric effect (https://en.wikipedia.org/wiki/Photoelectric_effect https://en.wikipedia.org/wiki/Photoelectric_effect).

yetihehe 5y ago
Yeah, there are many wrong and some disinformed statements in that article: > The most popular batteries use chemicals to store the energy. And then when we want to use the energy, we simply draw it back out. This is pretty much how the electrical grid works. No, electrical grid currently mostly works without batteries. Power stored in batteries which can give it back to grid is several orders of magnitude smaller than what grid transfers. But this may change in future. > Also, electricity can cause pressure (well can make things expand) [...] I could not find any current use cases for this property, I will have to look further. Ultrasonic scanners in doctors offices or ultrasonic motors for some camera lenses, or even those sound-playing birthday cards. > One you’ve seen a million times in the bath, but you never noticed. When bubbles pop, they can cause a small amount of light. This is called Sonoluminescence. They cause a really really small amount of light lasting a few hundred trillionths of a second. Yeah, but that's not electricity.
- jimhi 5y ago
  > Ultrasonic scanners in doctors offices or ultrasonic motors for some camera lenses, or even those sound-playing birthday cards. I am confused by your statement on this one. Birthday cards use tiny batteries. > Yeah, but that's not electricity. Perhaps the science was updated on this, but articles like this say they can get up to 1W out of it. https://physicsworld.com/a/brightest-bubble-bursting-yet/ https://physicsworld.com/a/brightest-bubble-bursting-yet/
  - yetihehe 5y ago
    > Birthday cards use tiny batteries. And piezoelectric buzzers https://en.wikipedia.org/wiki/Buzzer https://en.wikipedia.org/wiki/Buzzer > but articles like this say they can get up to 1W out of it Yeah, but they are getting electricity from light, sonoluminescence generates light, not electricity and author even singled out light as being something different than electricity, you can have light from electricity according to him.
    - jimhi 5y ago
      Interesting, thanks. Is there anything you know of that does the opposite? Uses pressure to generate electricity?
      - yetihehe 4y ago
        Piezoelectric crystals. Change in pressure causes electricity flow. They are used in piezoelectric lighters and in some microphones. Buzzers from birthday cards can work both ways, as a microphone (pressure->electricity) and as a speaker (electricity->pressure).

jleyank 5y ago

I naively thought that “electricity” is electrons moving from point a to point b under some potential (ie, a current). The electrons have to be able to move, which might be small in a conductor or higher in an insulator. And the photoelectric effect appears when photons of the appropriate energy blow electrons from the bound to the unbound state. Can’t say I recall a course that discussed the causes of electricity, so there must be a jargon problem here, I thought lightening came when the charge separation (or magnitude?) at the top of the cloud exceeded any insulation effect of the air. But then uni was a while ago. Fried various low voltage devices with static charges though, and I thought that was lightening writ small.