Question

Two charges are placed a certain distance apart in air. If a glass slab is introduced between them, the force between them will:

• A. increase
• B. decrease
• C. remains the same
• D. be zero

Answer 1

Answer: (B)

decrease

$F_{glass}=\frac{q_1{q}_2}{4\pi K{ϵ}_0{r}^2}=\frac{F}{K}$
As $K$ (for glass)$>1\therefore F_{glass}<F$

Dielectric constant of glass is greater than 1 hence, the force will decrease.