Question

将电阻R与用电器A串联接到电源两极,若电源电压恰好等于电器A的额定电压,A消耗的功率是13.5瓦,若把用电器A换成用电器

Answer 1

额定电功率：P(b)=U^2/R(b)=2*P(a)=2*U^2/R(a)

R(a)=2*R(b)

实际a分得电压：U(a)=U*R(a)/[R+R(a)]

电功率：P(a)=U²*R(a)/[R+R(a)]²=13.5w ①

实际b分得电压：U(b)=U*R(b)/[R+R(b)]

电功率：P(b)=U²*R(b)/[R+R(b)]²=17.28w ②

①②联立解得额定电压P(b)=48w

P(a)=24w