(1)正常加热时的功率:P1=440W;由P=UI.得:饮水机正常工作时电流:I=
=P U
=2A;440W 220V
(2)饮水机保温状态下,只有R1工作,此时功率:P2=40W;由:P=
,得:R1的阻值:R1U2 R
=U2 P2
=1210Ω;(220V)2
40W
(3)饮水机每加热4min,就显示保温状态16min,即每小时加热3次、保温3次;
故:加热时间:t1=3×4min=12min=12×60s=720s;保温时间:t2=3×16min=48min=48×60s=2880s;
饮水机一小时消耗的电能:W=W1+W2=P1t1 +P2t2=440W×720s+40W×2880s=4.32×105J.
答:(1)正常加热时通过饮水机的电流是2A;
(2)保温状态时电阻R1的阻值是1210Ω;
(3)饮水机一小时消耗的电能是4.32×105J.