Question

Stie cineva?......... ​

Answer 1

Punctul 1

Se aplica Legea lui Ohm pe tot circuitul.

$\displaystyle{ I =\frac{E}{R + r} }$

$\displaystyle{ I = \frac{ 12}{10+2} = \frac{12}{12} }$

I = 1 amper

Punctul 2

Se aplica Legea lui Ohm pe o portiune de circuit.

$\displaystyle{ I = \frac{U}{R} \rightarrow U = I \cdot R }$

$\displaystyle{ U = 1 \cdot 10 }$

U = 10 volti

Punctul 3

S = 4 mm² = $\displaystyle{ 4 \cdot 10^{-6} }$ m

$\displaystyle{ R = \frac{\rho\cdot l}{S} }$

$\displaystyle{ R = \frac{2 \cdot 10^{-7} \cdot 20}{4 \cdot 10^{-6} } = \frac{40 \cdot 10^{-7} }{4 \cdot 10^{-6} } }$

$\displaystyle{ R = 10 \cdot 10^{-1} = 10\cdot \frac{1}{10} }$

R = 1 ohm

$\displaystyle{ I = \frac{E}{R + r} }$

$\displaystyle{ I = \frac{12}{1 + 2} = \frac{12}{3} }$

Noua intensitate = 4 amperi