# Blog

A blog of Python-related topics and code.

## Python Quiz Advent Calendar: explanations

Here are the explanations for the Python Quiz Advent Calender puzzles which appear over December 2020.

## Uranium enrichment and the separative work unit (SWU)

Natural uranium consists largely of two isotopes, $\mathrm{^{235}U}$ and $\mathrm{^{238}U}$. The less-abundant (0.72%) isotope, $\mathrm{^{235}U}$ , is important for nuclear reactors and weapons because it is the only isotope existing in nature to any appreciable extent that can sustain a fission chain reaction (that is, it is fissile).

## Surface-to-volume ratios of some solid shapes

The shape with the minimum surface-to-volume ratio is the sphere. The code below plots this ratio for a variety of shapes as a function of a characteristic length:

## Langton's ant on a hexagonal plane

Langton's ant is a two-dimensional cellular automaton usually implemented on a square grid in which each cell has one of two states (white or black). The ant moves according to the simple rules:

## Visualizing vibronic transitions in a diatomic molecule

The Morse oscillator code introduced in a previous blog post can be used to visualize the vibronic transitions in a diatomic molecule by creating two Morse objects (one for each electronic state) and plotting their potential energy curves and energy levels on the same Matplotlib Axes object.