Question

Force between two point charges in air is F, if one third separation is filled by medium (e_r = 4), then force between charges becomes-

• A. $\frac{3}{4}$F
• B. $\frac{4}{3}$F
• C. $\frac{9}{16}$F
• D. None of these

Answer 1

Answer: (C)

$\frac{9}{16}$F

Answer 2

F = $\frac { 1 } { 4 \pi \epsilon _ { 0 } }$ .

F ' = $\frac { q _ { 1 } q _ { 2 } } { \left\{ \left( r - \frac { r } { 3 } \right) + \frac { r } { 3 } \sqrt { 4 } \right\} ^ { 2 } }$ =