Two charges +80 C and +20 C are separated by a distance in air. An unknown third charge q is placed at the centre of the line joining the two charges. If the charges are in equilibrium, then q .

Step-by-step solution

Given, Q₁=+80 C , Q₂=+20 C Let distance between charges be r. According to question, Since, charges are in equilibrium, aligned & k Q₁ q r^2 / 4 + k Q₁ Q₂ r^2 + k Q₂ q r^2 / 4 =0 & 4 k 80 q r^2 + k 80 20 r^2 + 4 k 20 q r^2 =0 & 4 80 q+4 20 q=-80 20 & 4 q+q=-20 & 5 q=-20 & q=-4 C & aligned