1 图所示电路由 4 个元件组成,电压电流的参考方向如图中所示。已知 U 1 = –5V , U 2 =15V , I 1 =2A , I 2 =3A , I 3 = –1A 。试计算各元件的电功率,并说明哪些元件是电源?哪些元 件是负载?
A.
P 1 = −10 ( W )是电源 P 2 = 40 ( W )是负载 P 3 = −15 ( W )是电源 P 4 = −20 ( W )是电源
B.
P 1 = −15 ( W )是电源 P 2 = 30 ( W )是负载 P 3 = −10 ( W )是电源 P 4 = −10 ( W )是负载
C.
P 1 = −10 ( W )是负载 P 2 = 20 ( W )是电源 P 3 = −20 ( W )是电源 P 4 = −30 ( W )是负载
D.
P 1 = −40 ( W )是负载 P 2 = 60 ( W )是负载 P 3 = −40 ( W )是电源 P 4 = −20 ( W )是负载