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B Charged basketball, inertia ball and field

  1. Jul 25, 2017 #1
    I was wondering how much I would have to charge a basket ball of mass M, so that I would begin to feel the inertia of the electrostatic field energy. We can calculate the total electrostatic field energy surrounding the charged basket ball, call it E. Can we then equate this energy E with a mass by E = mc^2? So that when the electrostatic energy surrounding the charged basket ball divided by the speed of light squared is a significant fraction of the mass of the basket ball we would notice the basket ball being harder to accelerate then an uncharged basket ball of mass M?

    Edit, at the same time that we begin to notice the inertia of the electrostatic field would we also notice the charged ball was harder to spin?

    Last edited: Jul 25, 2017
  2. jcsd
  3. Jul 25, 2017 #2


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    Charge by itself does not equate to energy. If a charge is present in an electric field, then you can say that the charge has electric potential energy, because the electric field has the potential to move the charge (much like a mass has gravitational potential energy, in a gravitational field).

    As far as "relativistic mass equivalent" behaving as you describe, I am uncertain, but I am pretty sure that is not the way it works. Photons have energy and can have momentum, yet they are massless.
    While adding charge can actually change the mass. Adding electrons to create net negative charge, and taking away electrons to create positive charge. Electrons do have a mass associated with them. Just something to think about.
  4. Jul 25, 2017 #3
    E near a charged ball will represent ELectric Field Intensity which is not Energy. So it can't be equated in energy. E or V are just two different visualisations of behavior of space around a charge (Region is called Electric Field).

    Energy here will be electric potential energy as scottdave said. But I'm not into relativity so can't figure out the last part.

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