sơ đồ mắc song song

R1//R2

a, =>\(Rtd=\dfrac{R1R2}{R1+R2}=\dfrac{20.20}{20+20}=10\left(ôm\right)\)

b,R1//R2//R3

\(=>\dfrac{1}{Rtd}=\dfrac{1}{R1}+\dfrac{1}{R2}+\dfrac{1}{R3}=\dfrac{1}{20}+\dfrac{1}{20}+\dfrac{1}{15}=>Rtd=6\left(ôm\right)\)c,

=>U1=U2=U3=30V

\(=>I1=\dfrac{U1}{R1}=\dfrac{30}{20}=1,5A,=>I2=\dfrac{U2}{R2}=1,5A\)

\(=>I3=\dfrac{U3}{R3}=2A\)

\(=>Im=\dfrac{U}{Rtd}=\dfrac{30}{6}=5A\)

a)Điện trở tương đương:

\(\dfrac{1}{R_{tđ}}=\dfrac{1}{R_1}+\dfrac{1}{R_2}+\dfrac{1}{R_3}=\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{16}=\dfrac{5}{16}\)

\(\Rightarrow R_{tđ}=\dfrac{16}{5}\Omega=3,2\Omega\)

b)\(R_1//R_2//R_3\Rightarrow U_1=U_2=U_3=U=2,4V\)

\(I_m=\dfrac{U}{R_{tđ}}=\dfrac{2,4}{3,2}=0,75A\)

\(I_1=\dfrac{U_1}{R_1}=\dfrac{2,4}{6}=0,4A\)

\(I_2=\dfrac{U_2}{R_2}=\dfrac{2,4}{12}=0,2A\)

\(I_3=I_m-I_1-I_2=0,15A\)

1. a. Theo ht 4' trg đm //, ta có:    Rtđ= (R1.R2)/(R1+R2)=    (3.6)/(3+6)=2 ôm

     b.Theo ĐL ôm, ta có:                  I= U/Rtđ=24/2=12 A

 I1=U/R1=24/3=8 ôm

 I2=U/R2=24/6=4 ôm

2. a. Theo ht 4' trg đm //, ta có:       Rtđ=(R1.R2.R3)/(R1+R2+R3)=     (6.12.4)/(6+12+4)=13,09 ôm

    b. Áp dụng ĐL Ôm, ta có:               U=I.R=3.13,09=39,27 V

    c. Theo ĐL Ôm, ta có: 

    I1=U/R1=39,27/6=6.545 A

    I2=U/R2=39,27/12=3,2725 A

    I3=U/R3=39,27/4=9.8175 A

1,

Rtđ =2 ôm

I=12 ôm

I1=8 ôm

I2=4 ôm

a)\(\dfrac{1}{R_{tđ}}=\dfrac{1}{R_1}+\dfrac{1}{R_2}+\dfrac{1}{R_3}=\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{16}=\dfrac{5}{16}\)

\(\Rightarrow R_{tđ}=\dfrac{16}{5}\Omega=3,2\Omega\)

b)\(I_m=\dfrac{U}{R_{tđ}}=\dfrac{2,4}{3,2}=0,75A\)

\(R_1//R_2//R_3\Rightarrow U_1=U_2=U_3=U=2,4V\)

\(I_1=\dfrac{U_1}{R_1}=\dfrac{2,4}{6}=0,4A\)

\(I_2=\dfrac{U_2}{R_2}=\dfrac{2,4}{12}=0,2A\)

\(I_3=I-I_1-I_2=0,75-0,4-0,2=0,15A\)

Lần sau bạn lưu ý chỉ đăng 1 lần thôi nhé, tránh làm trôi câu hỏi của người khác!

\(MCD:R1nt\left(R2//R3\right)\)

\(=>R=R1+R23=R1+\dfrac{R2\cdot R3}{R2+R3}=18+\dfrac{20\cdot30}{20+30}=30\Omega\)

\(=>I=I1=I23=\dfrac{U}{R}=\dfrac{12}{30}=0,4A\)

Ta có: \(U23=U2=U3=U-U1=12-\left(0,4\cdot18\right)=4,8V\)

\(=>\left\{{}\begin{matrix}I2=\dfrac{U2}{R2}=\dfrac{4,8}{20}=0,24A\\I3=\dfrac{U3}{R3}=\dfrac{4,8}{30}=0,16A\end{matrix}\right.\)

a. \(R=\dfrac{R1.R2}{R1+R2}=\dfrac{10.15}{10+15}=6\Omega\)

b. \(U=U1=U2=36V\)(R1//R2)

\(\Rightarrow\left\{{}\begin{matrix}I1=U1:R1=36:10=3,6A\\I2=U2:R2=36:15=2,4A\end{matrix}\right.\)

\(I'=I3=I=I1+I2=3,6+2,4=6A\left(R3ntR12\right)\)

a. Bạn tự vẽ ơ đồ mạch điện nhé!
b. \(R=\dfrac{R1.R2}{R1+R2}=\dfrac{20.30}{20+30}=12\left(\Omega\right)\)

b. \(U=U1=U2=12V\)(R1//R2)

\(\left\{{}\begin{matrix}I=U:R=12:12=1A\\I1=U1:R1=12:20=0,6A\\I2=U2:R2=12:30=0,4A\end{matrix}\right.\)