a. \(R_{23}=\dfrac{R_2.R_3}{R_2+R_3}=\dfrac{15.10}{15+10}=6\) (ôm)

\(\Rightarrow R_{tđ}=R_{23}+R_1=6+9=15\)(ôm)

b. Vì \(R_2\)//\(R_3\Rightarrow U_2=U_3\Leftrightarrow15I_2=10I_3\)

\(\Rightarrow I_3=\dfrac{15I_2}{10}=\dfrac{15.0,2}{10}=0,3\)(A)

\(\Rightarrow I_1=I_2+I_3=0,2+0,3=0,5\)(A)

c. ta có \(I=I_1=0,5\)

\(\Rightarrow U=I.R_{tđ}=0,5.15=7,5\)(V)

bn tự tóm tắt nhé

Giải

a,Ta có ( R2//R3)ntR1

nên Rtđ=\(\dfrac{R_2.R_3}{R_2+R_3}+R_1\)=\(\dfrac{15.100}{15+100}+9=\dfrac{507}{23}A\)

b,HĐT giữa hai đầu R2 là :

U2=I2.R2=0,2.15=3V

Ta lại có R2 //R3 =>U2=U3=3V

c đ d đ chạy qua R3 là :

I3=\(\dfrac{U_3}{R_3}=\dfrac{3}{100}=0,03A\)

=> \(I_1=I_2+I_3=0,2+0,03=0,23A\)

c, HĐT giữa 2 đầu R1,R23 là :

U1=I1.R1=0,23.9=2,07V

U23=I23.R23=0,23.\(\dfrac{15.100}{15+100}\)=\(\dfrac{39}{23}V\)

=> UAB = U1+U23=2,07+\(\dfrac{39}{23}\)\(\approx3,766V\)

ptmđ: (R₁//R₂)nt(R₃//R₄)ntR₅

a/ R_AB= \(\frac{R_1R_2}{R_1+R_2}+\frac{R_3R_4}{R_3+R_4}+R_5=\frac{2.3}{2+3}+\frac{4.6}{4+6}+1,4=5\left(\Omega\right)\)

b/ \(I=I_{12}=I_{34}=I_5=\frac{U_{AB}}{R_{AB}}=\frac{18}{5}=3,6\left(A\right)\)

\(U_{12}=U_1=U_2=I_{12}.R_{12}=3,6.1,2=4,32\left(V\right)\)

\(U_{34}=U_3=U_4=I_{34}.R_{34}=3,6.2,4=8,64\left(V\right)\)

\(U_5=I_5.R_5=3,6.1,4=5,04\left(V\right)\)

\(I_1=\frac{U_1}{R_1}=\frac{4,32}{2}=2,16\left(A\right)\)

\(I_2=\frac{U_2}{R_2}=\frac{4,32}{3}=1,44\left(A\right)\)

\(I_3=\frac{U_3}{R_3}=\frac{8,64}{4}=2,16\left(A\right)\)

\(I_4=\frac{U_4}{R_4}=\frac{8,64}{6}=1,44\left(A\right)\)

c/ \(Q_1=I_1^2.R_1.t=2,16^2.2.0,5.3600=16796,16\left(J\right)\)

\(Q_4=I_4^2.R_4.t=1,44^2.6.0,5.3600=22394,88\left(J\right)\)

\(Q_5=I_5^2.R_5.t=3,6^2.1,4.0,5.3600=32659,2\left(J\right)\)

\(\Rightarrow Q_1+Q_4+Q_5=16796,16+22394,88+32659,2=71850,24\left(J\right)\)

a/ R₂₃ = \(\dfrac{R_2.R_3}{R_2+R_3}\) = \(\dfrac{6.12}{6+12}\) = 4 Ω

R_td = R₁ + R₂₃ = 6 + 4 = 10 Ω

b/ I = I₁ = I₂₃ = \(\dfrac{U_{AB}}{R_{td}}\) = \(\dfrac{12}{10}\) = 1,2 A

U₂₃ = U₂ = U₃ = I₂₃ . R₂₃ = 1,2 . 4 = 4,8 V

I₂ = \(\dfrac{U_2}{R_2}\) = \(\dfrac{4,8}{6}\) = 0,8 A

I₃ = \(\dfrac{U_3}{R_3}\) = \(\dfrac{4,8}{12}\) = 0,4 A

c/ P = U.I = 12 . 1,2 = 14,4 W

d/ A = Q = P . t = 14,4 . (15.60) = 12960 J

hình vẽ đâu bạn???

Bạn vẽ hình mà (R1 nt R2) // ( R3 nt R4)

Mạch điện?

Bài 1:

a. \(R=R1+\left(\dfrac{R2.R3}{R2+R3}\right)=30+\left(\dfrac{15\cdot10}{15+10}\right)=36\Omega\)

b. \(I=I1=I23=\dfrac{U}{R}=\dfrac{24}{36}=\dfrac{2}{3}A\left(R1ntR23\right)\)

\(U23=U2=U3=I23\cdot R23=\dfrac{2}{3}\cdot\left(\dfrac{15.10}{15+10}\right)=4V\left(R2\backslash\backslash R3\right)\)

\(\rightarrow\left\{{}\begin{matrix}I2=U2:R2=4:15=\dfrac{4}{15}A\\I3=U3:R3=4:10=0,4A\end{matrix}\right.\)

Bài 2:

a. \(R=\dfrac{R1.\left(R2+R3\right)}{R1+R2+R3}=\dfrac{6\cdot\left(2+4\right)}{6+2+4}=3\Omega\)

b. \(U=IR=2.3=6V\)