Question

如图,电源电压为6V,R1为3千欧.当开关S分别跟触点1.2.3接通时,电压表示数分别为6V.3V.2V.则R1.R2.

Answer 1

S接蠋点1.2.3分别量的(R1+R2+R3);(R2+R3);R3在电路中的分压

所以接1:电压为点源电压 6V

接2:电压为(R2+R3)上电压 3V;则R1分压为 Vr1=(6-3)V =3V ,

所以电路中电流 I = Vr1/R1= 3/3000 = 0.001(A)

接3:R3的分压为2V 所以 R3 = Vr3/I = 2/0.001 = 2000(欧姆)

则 R2的分压为 Vr2 = V总 - Vr1 -Vr3 = 1(V)

所以 R2 = Vr2/I = 1/0.001 = 1000(欧姆)