(c) : Consider a thin spherical shell of radius x and thickness dx as shown in the figure.
![](https://www.sarthaks.com/?qa=blob&qa_blobid=1790100188888332011)
Volume of the shell, dV = 4πx2dx
Let us draw a Gaussian surface of radius r(r < R) as shown in the figure above.
Total charge enclosed inside the Gaussian surface is
![](https://www.sarthaks.com/?qa=blob&qa_blobid=15875040620908778892)