# Homework Help: Some questions on Special and Newtonian Relativity

1. Aug 22, 2009

### maverick280857

1. The problem statement, all variables and given/known data

Question 1: Is Ohm's Law (V = IR) invariant under Galilean transformations?
Question 2: Model the earth as an ellipsoid or a spheroid, and find the lowest order correction to the inverse square law at points inside and outside the earth's surface.

2. Relevant equations

--

3. The attempt at a solution

Question 1: Using the low velocity regime of the Lorentz transformations, we see that j = j', E = E' and so

[tex]j = \sigma E[/itex]

is invariant in both reference frames. As lengths are invariant under a Galilean transformation, this is equivalent to V = IR in all inertial frames. Is this correct?

Can this be argued without using the Lorentz transformations, i.e. without treating Galilean transformations as a special case of the Lorentz transformation for $v << c$?

(Also, can resistivity or conductivity be regarded as a Lorentz invariant scalar?)

Question 2: This has me stumped right now....I don't understand what has to be done here. I would appreciate if someone could point me in the right direction.

2. Aug 23, 2009

Anyone?