Question

Two point charges placed at a certain distance r in air exert a force F on each other. Then the distance r' at which these charges will exert the same force in a medium of dielectric constant k is given by

• A. r
• B. $\frac{r}{k}$
  
• C. $\frac{r}{\sqrt{k}}$
  
• D. $r\sqrt{k}$

Answer 1

The correct option is C $\frac{r}{\sqrt{k}}$


$F=For\frac{Q_1{Q}_2}{4\pi {ϵ}_0{r}^2}=\frac{Q_1{Q}_2}{4\pi {ϵ}_0{r}^{2}K}\Rightarrow r^{\prime }=\frac{r}{\sqrt{K}}$