Punctul 1
Se aplica Legea lui Ohm pe tot circuitul.
[tex]\displaystyle{ I =\frac{E}{R + r} }[/tex]
[tex]\displaystyle{ I = \frac{ 12}{10+2} = \frac{12}{12} }[/tex]
I = 1 amper
Punctul 2
Se aplica Legea lui Ohm pe o portiune de circuit.
[tex]\displaystyle{ I = \frac{U}{R} \rightarrow U = I \cdot R }[/tex]
[tex]\displaystyle{ U = 1 \cdot 10 }[/tex]
U = 10 volti
Punctul 3
S = 4 mm² = [tex]\displaystyle{ 4 \cdot 10^{-6} }[/tex] m
[tex]\displaystyle{ R = \frac{\rho\cdot l}{S} }[/tex]
[tex]\displaystyle{ R = \frac{2 \cdot 10^{-7} \cdot 20}{4 \cdot 10^{-6} } = \frac{40 \cdot 10^{-7} }{4 \cdot 10^{-6} } }[/tex]
[tex]\displaystyle{ R = 10 \cdot 10^{-1} = 10\cdot \frac{1}{10} }[/tex]
R = 1 ohm
[tex]\displaystyle{ I = \frac{E}{R + r} }[/tex]
[tex]\displaystyle{ I = \frac{12}{1 + 2} = \frac{12}{3} }[/tex]
Noua intensitate = 4 amperi
