Verified answer

U=3.5 B    L=50 м    S=2 мм2   po=0.028 Ом*мм2/м    I=?

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I=U/R

R=po*L/S

I=U*S/(po*L)=3.5*2/(0.028*50)=5 A

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R=ρL/S

R=U/I

ρL/S=U/I

I=US/ρL

I=3,5*50/0,028*2=63A