Hehe, I began to study the capacitor step-down circuit in the third grade, and there will definitely be development in the future! Although I made this thing in junior high school, it hasn't developed to capacitor step-down. But the capacitor step-down circuit is a college course (related to sinusoidal steady-state analysis of alternating current), and high school mathematics needs polar coordinate operation and complex number operation. I gave you the formula, and I guess you won't use it either. These formulas can only be used after learning relevant mathematics knowledge in senior high school.

When the power supply voltage is 220V, the partial voltage of the capacitor is 220-50= 170V, and the current flowing through the capacitor is 1.5A (actually, the actual current flowing through the capacitor should be 1.5 ∠ 90 due to the change of the phase angle of the capacitor to alternating current). According to ohm's law, z = u/r =170 ∠ 0 ∠1.5 ∠ 90 =146 ∠ 90, and capacitive reactance ZC =1/j ω c.