a)
[tex]Dane:\\R \ \ i \ \ U\\Szukane:\\P = ?\\\\P = U\cdot I\\\\ale\\\\R = \frac{U}{I} \ \ \rightarrow \ \ I = \frac{U}{R}\\\\P = U\cdot\frac{U}{R}\\\\\boxed{P = \frac{U^{2}}{R}}[/tex]
b)
[tex]Dane:\\R \ \ i \ \ I\\Szukane:\\P = ?\\\\P = U\cdot I\\\\ale\\\\R = \frac{U}{I} \ \ \rightarrow \ \ U = R\cdot I\\\\P = R\cdot I\cdot I\\\\\boxed{P = I^{2}\cdot R}[/tex]
