In one of my books there is a figure
where G is a neon lamp. Basically the capacitor gets charged once the switch is closed up to a certain spark-current $U_Z$ where the neon lamp gets switched on so the capacitor can discharge to a certain charge-current $U_L$. Further it says that from the charging current
of the capacitor it follows that the periodicity is
How exactly does this equation follow? I am not familiar with the proper english terms in electrical engineering so I might have mixed up voltage, current, etc. I hope, it's still clear what I mean.