Question

ajutooor, dau coronita

Answer 1

$R=300 \ \Omega \\ I=5 \ A \\ \rho=30 \cdot 10^{-8} \ \Omega \cdot m \\ S=1 \ mm^2=10^{-6} \ m^2 \\ \boxed{R=\rho \cdot \frac{l}{S}} \ \ \ \boxed{I=\frac{U}{R}} \\ l=\frac{R \cdot S}{\rho}=\frac{300 \ \Omega \cdot 10^{-6} \ m^2}{30 \cdot 10^{-8} \ \Omega \cdot m^2}=10 \cdot 0,75 \ m \\ \Rightarrow \boxed{\bold{l=7,5 \ m}} \\ U=I \cdot R =5 \ A \cdot 300 \ \Omega \\ \Rightarrow \boxed{U=1 \ 500 \ V}}$