Return to Video

08-23 Stealing Charge from the Earth

  • 0:00 - 0:03
    It turns out this actually another method to charge by induction.
  • 0:03 - 0:06
    This method, just like the first method, also uses two spheres
  • 0:06 - 0:10
    but here, one of those spheres is actually the earth.
  • 0:10 - 0:15
    Let's say you have your conducting sphere and it's attached to the ground by a conducting rod.
  • 0:15 - 0:17
    Let's also add a bunch of wires that extend into the ground
  • 0:17 - 0:22
    and then let's hold a positive charge over our conducting sphere.
  • 0:22 - 0:26
    What's going to happen is that we're going to actually draw electrons from the earth.
  • 0:26 - 0:31
    If we then detached this sphere, we can even remove the positive charge
  • 0:31 - 0:34
    and now here we have it, a negatively charged sphere.
  • 0:34 - 0:37
    And this negative charges somehow came from the ground.
  • 0:37 - 0:40
    Now, of course, this must mean that throughout the earth,
  • 0:40 - 0:43
    there must be a few extra positive charges lingering around.
  • 0:43 - 0:45
    They've lost their electrons.
  • 0:45 - 0:48
    It seems like if we were to do this experiment over and over and over,
  • 0:48 - 0:52
    well, eventually we'd have a positively charged earth and that might be a problem.
  • 0:52 - 0:55
    It turns out that this is a non-issue and I want you to tell me
  • 0:55 - 0:58
    why you think this works and why it's a non-issue?
  • 0:58 - 1:01
    Maybe you think the earth is somehow able to create electrons
  • 1:01 - 1:05
    create this negative charges, so that actually there's no residual positive charge leftover.
  • 1:05 - 1:08
    Maybe it has something to do with the fact that the earth is huge.
  • 1:08 - 1:11
    Maybe that has something to do with the reason why this never becomes a problem
  • 1:11 - 1:14
    where we actually wind up charging the earth with some noticeable amount.
  • 1:14 - 1:19
    Or maybe you think the earth is an insulator, something in which charges cannot move
  • 1:19 - 1:23
    and that this somehow saves us and allows this whole process to work.
  • 1:23 -
    Check what you think is the best answer.
Title:
08-23 Stealing Charge from the Earth
Team:
Udacity
Project:
PH100 - Intro to Physics
Duration:
01:26
Amara Bot added a translation

English subtitles

Revisions