eletromagnetismo

\(\[\begin{align} & Um\text{ }anel\text{ }carregado\text{ }possui: \\ & Q\text{ }=\text{ }carga\text{ }total\text{ }positiva \\ & P\text{ }=\text{ }campo\text{ }el\acute{e}trico \\ & z=\text{ }dist\hat{a}ncia\text{ }do\text{ }plano\text{ }do\text{ }anel,\text{ }em\text{ }seu\text{ }eixo. \\ & Componentes\text{ }paralelas\text{ }do\text{ }eixo\text{ }z: \\ \end{align}\] \)

\(\[\begin{align} & \\ & d{{{\vec{E}}}_{||}}=\hat{z}k\frac{dq}{{{r}^{2}}}\cos \theta =\hat{z}kdq\frac{z}{{{r}^{3}}} \\ & \frac{z}{{{r}^{3}}}: \\ & {{{\vec{E}}}_{||}}=\int{d}{{{\vec{E}}}_{||}}=\hat{z}k......acz{{r}^{3}}Q=\hat{z}kQ\frac{z}{{{\left( {{a}^{2}}+{{z}^{2}} \right)}^{3/2}}} \\ & Logo,z>>a: \\ & {{{\vec{E}}}_{||}}\approx \hat{z}\frac{kQ}{{{z}^{2}}} \\ \end{align}\] \)