Question

Mn giúp mình với ạ

Answer 1

\(a,\)\(\Rightarrow\left\{{}\begin{matrix}Ud=Ub=3V\\Id=Idm=\dfrac{Ud}{Rd}=0,5A\end{matrix}\right.\)

\(\Rightarrow U1=U-Ud=6-3=3V\Rightarrow I1=\dfrac{U1}{R1}=0,75A\)

\(\Rightarrow Ib=I1-Id=0,25A\Rightarrow Rb=\dfrac{Ub}{Ib}=\dfrac{3}{0,25}=12\Omega\)

\(b,\Rightarrow Id=\dfrac{Ud}{Rd}=\dfrac{U-U1}{6}=\dfrac{6-Im.R1}{6}=\dfrac{6-\dfrac{6.4}{R1+\dfrac{Rb.Rd}{Rb+Rd}}}{6}=\dfrac{6-\dfrac{24}{\dfrac{24+10Rb}{6+Rb}}}{6}=\dfrac{36Rb}{6\left(24+10Rb\right)}=\dfrac{6Rb}{24+10Rb}=\dfrac{6}{\dfrac{24}{Rb}+10}\left(A\right)\)

\(\Rightarrow Rb\uparrow\Rightarrow\dfrac{24}{Rb}+10\downarrow\Rightarrow Id=\dfrac{6}{\dfrac{24}{Rb}+10}\uparrow\)

=>do sang den tang