1. PF Contest - Win "Conquering the Physics GRE" book! Click Here to Enter
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Grounding is used for dircharging In case of charging by

  1. Feb 7, 2010 #1
    Grounding is used for dircharging..
    In case of charging by conduction,let a sphere having excess negative charge is brought in contact with a neutral sphere..Half of the negative charge goes into neutral sphere..But when the former sphere having excess negative charge is grounded,why it becomes neutral? Why does it lose all the charge ?
  2. jcsd
  3. Feb 7, 2010 #2
    Re: Grounding

    The transported charge depends on the size of the sphere. The earth is pretty large.
  4. Feb 7, 2010 #3
    Re: Grounding

    Yes..It is but why it neutralizes the sphere? Why its different from case when 2 identical spheres ,one negatively charged nd one neutral share charge by conduction?
  5. Feb 7, 2010 #4
    Re: Grounding

    I think he's saying it shares yes, but depending on size, so if one is twice as big as the other it would get 2/3 the charge and the other would get 1/3, so if one is 100x as large it would get 99.01% of the charge... and so on..
  6. Feb 7, 2010 #5
    Re: Grounding

    Another way to think of it is in terms of capacitance: Q = CV -> dV/dQ = 1/C. If you discharge to something with low capacitance (your sphere) then it's voltage will change fairly quickly, perhaps not allowing you to totally discharge. If the capacitance is huge (earth), then voltage will remain constant allowing full discharge.
  7. Feb 7, 2010 #6
    Re: Grounding

    Oh..I understand now.. Thank u all
  8. Feb 7, 2010 #7
    Re: Grounding

    In case of charging with induction,when a positive rod is brought near the left side of neutral sphere,electron start moving to left and right side becomes postive due to lack of electrons.Now if we ground that sphere from right side and don't move the rod?Will electrons flow from ground to the sphere ?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook