✔ 最佳答案
The power supply in Hong Kong is 220V,
The resistance of the 60W lamp is P=V^2/R,60=220^2/R,R=806.7ohm
The resistance of the 100W lamp is P=V^2/R,100=220^2/R,R=484ohm
When they connect in series,by V=IR,220=I(806.7+484),I=0.170A,
Since it is connect in series the current is constant.
The power of the 60W lamp in series circuit,P=I^2R,P=0.17^2*806.7,
P=23.3W
The power of the 100W lamp in series circuit,P=I^2R,P=0.17^2*484
P=14.0W
Since the power of the 60W lamp is greater than the 100W lamp,
60W lamp is brighter than a 100W lamp when they are connected in series