### Atoms

goals
The key feature of Bohr's theory of spectrum of hydrogen atom is the quantization of angular momentum when an electron is revolving around a proton. We will extend this to a general rotational motion to find quantized rotational energy of a diatomic molecule assuming it to be rigid. The rule to be applied is Bohr's quantization condition.
Consider a gold nucleus to be a sphere of radius $6\cdot\ 9$ Fermi in which protons and neutrons are distributed. Find the force of repulsion between two protons situated at largest separation. Why do these protons not fly apart under this repulsion ?
In a set of experiments on a hypothetical one-electron atom, the wavelengths of the photons emitted from transitions ending in the ground state $(n=1)$ are shown in the energy diagram above.

$\propto$-particles are scattered by the gold nucleus but not by the electrons.
It is, because

Which is de-Broglie wavelength of a $3\ kg$ object moving with a speed of $2\ m/s$?