u=√2sin1200πt v，u有效值=1v，ω=1200π，U=1∠0°；Xc=1/jωC=-j26.5k，Uc=-j26.5k/(R-j26.5k)=-j26.5k(R+j26.5k)/(R²+26.5k²)=26.5k(26.5k-jR)/(R²+26.5k²) ，tan∠-60°=-1.732=-R/26.5k，R≈46k。Uc=0.49v。
