• # question_answer A conducting sphere of radius 10 cm is charged with$\text{10}\mu \text{C}\text{.}$Another uncharged sphere of radius 20 cm is allowed to touch it for some time. After, if the spheres are separated, then the surface density of charges on the spheres will be in the ratio of A)  1:4                             B)  1:3C)  1:2                             D)  1:1

Here,${{r}_{1}}=10cm,{{q}_{1}}=10\mu \,C,{{r}_{2}}=20cm$ As $\frac{{{\sigma }_{1}}}{{{\sigma }_{2}}}=\frac{{{r}_{1}}}{{{r}_{2}}}\therefore \frac{{{\sigma }_{1}}}{{{\sigma }_{2}}}=\frac{10}{20}=\frac{1}{2}.$ Hence, the correction option is [c].