KVPY SX SB Exam 2012 Question Paper

In one model of the electron, the electron of mass ${\mathit{m}}_{\mathit{e}}$ is thought to be a uniformly charged shell of radius R and total charge e, whose electrostatic energy E is equivalent to its mass ${\mathit{m}}_{\mathit{e}}$ via Einstein’s mass energy relation $\mathit{E}={\mathit{m}}_{\mathit{e}}{\mathit{c}}^2$. In this model, R is approximately $({\mathit{m}}_{\mathit{e}}=9.1\times {10}^{-31}\mathrm{kg}$ $,\mathit{c}=3\times {10}^8\mathit{m}.{\mathit{s}}^{-1}$ , $1∕4\mathit{\pi }{\mathit{\epsilon }}_0=9\times {10}^9$ Farads.m${}^{-1}$, magnitude of the electron charge $=1.6\times {10}^{-19}$ C)