The electric field intensity on the surface of a solid charged sphere of radius ' $r$ ' and volume charge…

The electric field intensity on the surface of a solid charged sphere of radius ' $r$ ' and volume charge density ' $\rho$ ' is ( $\varepsilon_0=$ permittivity of free space $)$
  1. $\frac{\rho r}{3 \varepsilon_0}$
  2. $\frac{\rho}{4 \pi \varepsilon_0 r}$
  3. zero
  4. $\frac{5 \rho \mathrm{r}}{6 \varepsilon_0}$

Solution

According to Gauss' theorem, $\phi=\mathrm{E} \cdot \mathrm{A}=\frac{\mathrm{q}_{\mathrm{enc}}}{\varepsilon_0}$ But, $\mathrm{q}_{\text {enc }}=\rho \times$ volume $\therefore \quad \mathrm{q}_{\mathrm{enc}}=\rho\left(\frac{4}{3} \pi \mathrm{r}^3\right)$ And area is $A=4 \pi r^2$ $\begin{aligned} & \therefore \quad \mathrm{E}\left(4 \pi \mathrm{r}^2\right)=\frac{\rho\left(\frac{4}{3} \pi \mathrm{r}^3\right)}{\varepsilon_0} \\ & \therefore \quad \mathrm{E}=\frac{\rho \mathrm{r}}{3 \varepsilon_0} \end{aligned}$ *

Asked in: MHT CET 2023 (14 May Shift 1)

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