Răspuns:
Se dă:
R₁ = R₂ = 20Ω
R₃ = 30Ω
R₄ = 10Ω
Figura II.43 a)
[tex]\frac{1}{R_{23}} = \frac{1}{R_{2}}+ \frac{1}{R_{3}}\\\\ R_{23} =\frac{R_{2}*R_{3}}{R_{2}+R_{3}} = \frac{20*30}{20+30} = \frac{500}{50} = 10[/tex]Ω
R(total) = R₁ + R₂₃ + R₄ = 20 + 10 + 10 = 40Ω
Figura II.43 b)
[tex]\frac{1}{R_{123}} = \frac{1}{R_{1}} + \frac{1}{R_{2}} + \frac{1}{R_{3}}\\\\ R_{123} =\frac{R_{1}* R_{2}*R_{3}}{R_{2}R_{3}+R_{1}R_{3}+R_{1}R_{2}} = \frac{20*20*30}{20*30+20*30+20*20}=\frac{20*20*30}{20(30+30+20)} =[/tex]
[tex]= \frac{20*30}{80} = \frac{30}{4} = 7,5[/tex]Ω
R(total) = R₁₂₃ + R₄ = 7,5 + 10 = 17,5Ω
Figura II.43 c)
R₁₄ = R₁ + R₄ = 20 + 10 = 30Ω
[tex]\frac{1}{R_{23}} = \frac{1}{R_{2}}+ \frac{1}{R_{3}}\\\\ R_{23} =\frac{R_{2}*R_{3}}{R_{2}+R_{3}} = \frac{20*30}{20+30} = \frac{500}{50} = 10[/tex]Ω
[tex]\frac{1}{R_{(total)}} = \frac{1}{R_{14}} + \frac{1}{R_{23}} \\\\R_{(total)} = \frac{R_{14}*R_{23}}{R_{14} + R_{23}} = \frac{30*10}{30+10} = \frac{300}{40} = \frac{30}{4} = 7,5[/tex]Ω
