Yuba is a household appliance installed in the bathroom for heating and lighting. The nameplate and simplified circuit of a brand of Yuba are shown in the figure, L is the lighting lamp, L 1, L 2.

(1) When the Yuba works, in order to maximize the heating power, two infrared heating lamps with the power of 275W need to work at the same time, so the switch S 1S2 is closed.

So the answer is: S 1S2.

(2) When the lamp works, its resistance is r = U2P2P = (220v) 2 40w =1210 ω.

Answer: When the lamp works, its resistance is1210Ω.

(3) Three Lamps District works normally for half an hour at the same time, and the power consumption is W=P, t+P, t = 0.04kw× 0.5h+0.55kw× 0.5h = 0.295kw? h.

Answer: Three Lamps District works normally for half an hour at the same time, and consumes 0.295kw of electricity? h.