Question

Cho (((R1 song song R2 ) nối tiếp R3) song song R4)
Cho R1= 10 \(\Omega\) ; R2= 20 \(\Omega\); R3= 30\(\Omega\) ;R4= 40\(\Omega\) ;U= 60V
Tính Rtương đương = ?; Tính I, I1, I2, I3, I4.
**Giải chi tiết**

Answer 1

ta có sơ đồ:

Ta có: R₁₂=\(\dfrac{R_1R_2}{R_1+R_2}=\dfrac{10.20}{10+20}=\dfrac{200}{30}=\dfrac{20}{3}\left(\Omega\right)\)

R₁₂₃=R₁₂+R₃=\(\dfrac{20}{3}+30=\dfrac{110}{3}\left(\Omega\right)\)

=> R_td=R₁₂₃₄=\(\dfrac{R_{123}R_4}{R_{123}+R_4}=\dfrac{\dfrac{110}{3}.40}{\dfrac{110}{3}+40}=\dfrac{440}{23}=19,13\left(\Omega\right)\)

=> I=\(\dfrac{U}{R_{td}}=\dfrac{90}{\dfrac{440}{23}}=\dfrac{207}{44}=4,7\left(A\right)\)

Lại có:

U=U₄=U₁₂₃=90(V)

=> I₄=U₄:R₄=90:40=2,25(A)

I₁₂=I₃=U₁₂₃:R₁₂₃=\(\dfrac{90}{\dfrac{110}{3}}=2,45\left(A\right)\)

U₁₂=U₁=U₂=U-U₃=U-I₃R₃=90-\(\dfrac{27}{11}.30\)=\(\dfrac{180}{11}=16,36\left(V\right)\)

=> I₁=\(\dfrac{U_1}{R_1}=\dfrac{\dfrac{180}{11}}{10}=\dfrac{18}{11}=1,636\left(A\right)\)

I₂\(=\dfrac{U_2}{R_2}=\dfrac{\dfrac{180}{11}}{20}=\dfrac{9}{11}=0,818\left(A\right)\)