Question

Two spherical conducters $B$ and $C$ having equal radii and carrying equal charge in them repel each other with a force $F$ when kept at some distance. A third spherical conductors of same radii but uncharged is brought in contact with $B$ and brought in contact with $C$ and finally removed away from both. The new force of repulsion between $B$ and $C$ is :-

• A. $F/4$
• B. $3F/4$
• C. $F/8$
• D. $3F/8$

Answer 1

Answer: (D)

$F=\frac{K{Q}^2}{r^2}$
$F^{{}^{\prime }}=K\left(\frac{Q}{2}\right)\left(\frac{3Q}{4}\right)$
$F^{{}^{\prime }}=\frac{3}{8}F$