User talk:Gurde

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Response to question at Talk: Electromagnetic induction
The choice of constants for a unit system is arbitrary, but you're right in that 4&pi; must appear somewhere in the equations regardless of unit system due to the total solid angle. So SI has simply chosen to have their 4&pi; in Coulombs law, whereas Gauss's law is without it:


 * $$ \mathbf{E} = \frac{1}{4 \pi \varepsilon_0} \frac{q}{r^2}$$ and $$\oint \mathbf{E} \cdot d \mathbf{s} = Q_{enclosed} / \varepsilon_0$$

For comparison, in Gaussian units the same equations are


 * $$ \mathbf{E} = \frac{q}{r^2}$$ and $$ \oint \mathbf{E} \cdot d \mathbf{s} = 4 \pi Q_{enclosed}$$

So you hit the nail on the head. &mdash; Laura Scudder | Talk 16:46, 1 October 2005 (UTC)