1.P=UI得I=P/U
100W/220V=5/11A
2.I=U/R得R=U/I
220V/(11分之5A)=484欧
4.P=U^2/R得
110V^2/484=25W
3.P=W/T得
T=W/P
T=1KWH/0.1KW=10H