The physics
A resistor's current is in step with the voltage. A coil's current lags by a quarter cycle. A capacitor's current leads by a quarter cycle.
XL = ωL = 2πfL XC = 1 / (ωC)
A phasor is an arrow that turns at ω. The height of its tip is the value at that instant. Voltages and currents a quarter cycle apart are arrows at 90°.
In a series circuit the same current flows through every part. The parts' voltages add as arrows, not as numbers.
Z = √(R² + (XL − XC)²) tan φ = (XL − XC) / R
A plain “220 V” is an rms value. V₀ in V₀ sin ωt is the peak, and V₀ = √2 Vrms.