Question

Subiectul 1 sau 2 va rog...

Answer 1

$\displaystyle Subiectul~I\\ \\ 1.~Q=600~C;~\Delta t=10~min\\ \\ \Delta t=10~min =600~s\\ \\ Q=I \Delta t \Rightarrow I=\frac{Q}{\Delta t} \Rightarrow I=\frac{600}{600} \Rightarrow I=1~A\\ \\ R:\mathbf{b}\\ \\ 2.~R:\mathbf{c}\\ \\ 3.~\frac{U}{I} =\frac{V}{A} =\Omega\\ \\ R:\mathbf{d}\\ \\ 4.~R:\mathbf{a}$

$\displaystyle 5.~\eta=\frac{R}{R+r} \\ \\ \eta_1=\frac{R_1}{R_1+r} ;~\eta_2=\frac{R_2}{R_2+r} \\ \\ \frac{\eta_1}{\eta_2} =\frac{\frac{R_1}{R_1+r}}{\frac{R_2}{R_2+r} }=\frac{R_1}{R_1+r}\cdot \frac{R_2+r}{R_2}=\frac{R_1(R_2+r)}{R_2(R_1+r)} \\ \\ R:\mathbf{a}$

$\displaystyle Subiectul~II\\ \\ a.~U_1=IR_1 \Rightarrow R_1=\frac{U_1}{I} \Rightarrow R_1=\frac{4}{2} \Rightarrow \mathbf{R_1=2~\Omega}\\ \\ b.~\frac{1}{R_p} =\frac{1}{R_2} +\frac{1}{R_3} \Rightarrow \frac{1}{R_p} =\frac{R_2+R_3}{R_2R_3} \Rightarrow R_p=\frac{R_2R_3}{R_2+R_3} \Rightarrow R_p=\frac{6\cdot3}{6+3} \Rightarrow \\ \\ \Rightarrow R_p=\frac{18}{9} \Rightarrow R_p=2~\Omega\\ \\ R_e=R_A+R_1+R_p\Rightarrow R_e=R_A+2+2 \Rightarrow R_e=R_A+4\\ \\ E_e=E_1+E_2\Rightarrow E_e=10+22 \Rightarrow E_e=32~V$

$\displaystyle r_e=r_1+r_2\Rightarrow r_e=1+1\Rightarrow r=2~\Omega\\ \\ I=\frac{E_e}{R_e+r_e} \Rightarrow 2=\frac{32}{R_A+4+2} \Rightarrow 2=\frac{32}{R_A+6} \Rightarrow 2(R_A+6)=32 \Rightarrow \\ \\ \Rightarrow 2R_A+12=32 \Rightarrow 2R_A=32-12 \Rightarrow 2R_A=20 \Rightarrow R_A=\frac{20}{2} \Rightarrow \\ \\ \Rightarrow \mathbf{R_A=10~\Omega}\\ \\ c.~u_2=Ir_2 \Rightarrow u_2=2 \cdot 1 \Rightarrow \mathbf{u_2=2~V}$

$\displaystyle d.~I=\frac{-E_1+E_2}{R_e+r_e} \\ \\ R_e=R_A+4\Rightarrow R_e=10+4 \Rightarrow R_e=14~\Omega\\ \\ I=\frac{-10+22}{14+2} \Rightarrow I=\frac{12}{16} \Rightarrow \mathbf{I=0,75~A}$