(1)电磁炉1min内消耗的电能:W1=
=0.03kW?h;90revs 3000revs/(kW?h)
电磁炉的实际功率为:
P=
=W1 t1
=1800W;0.03×3.6×106J 1×60s
(2)电磁炉在烧水过程中吸收的热量:Q吸=cm△t=4.2×103J/(kg?℃)×3kg×(100℃-25℃)=9.45×105J;
则η=
×100%=Q吸 W
×100%=87.5%.9.45×105J 1800W×10×60s
答:(1)电磁炉的实际功率为1800W;
(2)电磁炉在烧水过程中的效率是87.5%.