[tex]Dane:\\A_1 = 10 \ cm = 0,1 \ m\\A_2 = 0,3 \ m\\k_1=k_2 = k\\Szukane:\\\frac{E_2}{E_1}=?\\\\Rozwiazanie\\\\E = \frac{1}{2}kA^{2}\\\\E_1 =\frac{1}{2} kA^{2}_1\\\\E_2 = \frac{1}{2}kA^{2}_2\\\\\frac{E_2}{E_1} = \frac{\frac{1}{2}kA^{2}_2}{\frac{1}{2}kA^{2}_1}=\frac{A^{2}_2}{A^{2}_1} = \frac{0,3^{2}}{0,1^{2}} =3^{2} =\underline{ 9}[/tex]
Odp. Wzrosła 9-krotnie.