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1. ### Ionic spectra for helium

[b]1. The emission line of He II at 468.6 nm corresponds to what electronic transition? [b]2. I know that the formula 1 / λ = R(1 / nb2 - 1/ na2) may be useful but I'm not sure how the Rydberg's constant would change since it's helium. Also, I'm not sure what to assume as the initial energy...
2. ### Electric potential, solution to Laplace's Eq.

Homework Statement Prove that the potential outside of any radially symmetric charge distribution of total charge q, given by, V = q/(4*pi*epsilon_0*r) is a solution to Laplace's Equation. Hint: Only a masochist would solve this problem by solving Laplace's Equation. It is much...
3. ### Forces between molecules

I think what you've said so far is fairly correct. This also ties in with the fact that attractive forces have a negative sign associated with them, and repulsive forces are positive by convention.
4. ### Calculating size of charge distribution with a known electric field

Homework Statement A complicated distribution of 10 protron produces a radially symmetric electric field given by, E(r) = (10*charge_of_proton/4pi*epsilon_0)*(1/r^2 + 100/r^4)*r_hat Give an order of magnitude estimate for the size of the charge distribution. Homework Equations...