Salutare!
Cunoaștem:
[tex]\rho = 2,8\times 10^{-8}\\l = 400 \ m\\U = 2 \ V\\I = 0,24 \ A[/tex]
Formule:
[tex]R = \rho \times\frac{l}{S}[/tex]
[tex]R = \frac{U}{I}[/tex]
[tex]\frac{U}{I} = \frac{\rho \times l}{S}[/tex]
[tex]S = \frac{I \times \rho \times l}{U}[/tex]
Înlocuire cu valori numerice:
[tex]S = \frac{0,24 \times 2,8 \times 10^{-8} \times 400}{2} \\ \\ S = 0,24 \times 2,8 \times 10^{-8} \times 200\\ \\ S = 0,672 \times 10^{-8} \times 200 \\\\\boxed{S = 134,4 \times 10^{-8} \ m^2}[/tex]
