a. \(R=R1+\dfrac{R2\cdot R3}{R2+R3}=14+\dfrac{24\cdot8}{24+8}=20\Omega\)
b. \(I=I1=I23=U:R=16:20=0,8A\left(R1ntR23\right)\)
\(U23=U2=U3=I23\cdot R23=0,8\cdot\dfrac{24\cdot8}{24+8}=4,8V\left(R2//R3\right)\)
\(\rightarrow\left\{{}\begin{matrix}I2=U2:R2=4,8:24=0,2A\\I3=U3:R3=4,8:8=0,6A\end{matrix}\right.\)
c. \(Q_{toa}=A=UIt=16\cdot0,8\cdot15\cdot60=11520\left(J\right)\)
d. \(R3=p3\dfrac{l3}{S3}\Rightarrow l3=\dfrac{R3\cdot S3}{p3}=\dfrac{8\cdot0,02\cdot10-6}{0,4\cdot10^{-6}}=0,4\left(m\right)\)
a)\(R_{23}=\dfrac{R_2\cdot R_3}{R_2+R_3}=\dfrac{24\cdot8}{24+8}=6\Omega\)
\(R_{tđ}=R_1+R_{23}=14+6=20\Omega\)
b)\(I_1=I_{23}=I_m=\dfrac{U}{R}=\dfrac{16}{20}=0,8A\)
\(U_2=U_3=U_{23}=6\cdot0,8=4,8V\)
\(I_2=\dfrac{4,8}{24}=0,2A;I_3=\dfrac{4,8}{8}=0,6A\)
c)\(Q=RI^2t=20\cdot0,8^2\cdot15\cdot60=11520J\)
d)Chiều dài dây:
\(R_3=\rho\cdot\dfrac{l}{S}\Rightarrow l=\dfrac{R_3\cdot S}{\rho}=\dfrac{8\cdot0,02\cdot10^{-6}}{0,4\cdot10^{-6}}=0,4m=40cm\)
