Question 80 of 311

Graphical variation of electric field due to a uniformly charged insulating solid sphere of radius $R,$with distance $r$ from the centre $O$ is represented by:

ADig
BCD

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Answer: (A) Dig

The electric field inside a solid insulated sphere is given by
${E}_{inside}=\dfrac{\rho r}{3{\epsilon }_{0}}$ for $r\lt R$ where $\rho$ is volume charge density.
Hence, the electric field varies linearly with the distance as
${E}_{inside}\propto {r}^{1}$
Now, the electric field for $r\gt R$ is given by
${E}_{outside}=\dfrac{Q}{4\pi {\epsilon }_{0}{r}^{2}}$
${E}_{outside}\propto \dfrac{1}{{r}^{2}}$
Thus, the graph starts decreasing as a power law graph as shown in the figure for the region $r\gt R$.
Hence, this graph is the right option.

JEE Main Physics practice question on Electrostatics (Electric Field and Electric Field Lines), with the answer and a step-by-step solution. Scan a question from your own book or paper to get a whiteboard video.