Solid State Physics - Formulas

Would you like to solve a physical or mathematical problem, but you just do not get into the quantitative context? And that, even though you have dealt with the respective topic in the universal book of knowledge and have looked at a learning video?

That's why the formula wand of the universal thinker comes to your aid! Just as I disarm the opponent with "Expelliarmus", so do you apply an appropriate spell formula to your problem to defeat it.