MCQ
A force ‘F’ is acting between two charges in air. If the space between them be completely filled with a medium K = 4, the force will be:
- AF
- B4F
- C$\frac{\text{F}}{4}$
- D2F
✓
Answer
- $\frac{\text{F}}{4}$
Explanation:
By Coulomb's law, the force between two charges (q1, q2) in air is given by
$\text{F}=\frac{\text{q}_1\text{q}_2}{4\pi\in_{0}\text{r}^2}$
where r= distance between two charges.
Now the force between two charges (q1, q2) in medium with dielectric
constant K = 4 becomes, $\text{F}=\frac{\text{q}_1\text{q}_2}{4\pi\text{K}\in_{0}\text{r}^2}$
So, $\text{F}=\frac{\text{F}}{\text{K}}=\frac{\text{F}}{4}$
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