1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    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!

Inverse-square law

  1. Oct 29, 2008 #1
    If the intensity of electromagnetic radiation (I) is equal to the power emitted (P) divided by the area of the sphere (4pi(r^2)) that it radiates, why is the inverse-square law 1/(r^2) instead of P/(4pi(r^2))? Shouldn't the radiation emitted propagate isotropically in all directions (sphere) instead of anisotropically (cube)? I apologize for the notation; I don't know how to write in latex. Thank you.
     
  2. jcsd
  3. Oct 29, 2008 #2

    rbj

    User Avatar

    the [itex]4 \pi[/itex] factor can just be folded into the "k" or "G" factor we see in inverse-square laws. either way, they're inverse-square.

    but, i agree with your sentiments, which is why i think that more natural Planck Units would be those that normalize [itex]4 \pi G[/itex] instead of just [itex]G[/itex] and it would be better to choose a natural unit of charge that would normalize [itex]\epsilon_0[/itex] instead of normalizing [itex]4 \pi \epsilon_0[/itex].
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Inverse-square law
  1. Inverse square law (Replies: 5)

  2. Inverse Square Law (Replies: 9)

  3. Inverse square law (Replies: 8)

Loading...