NEET2017PhysicsElectrostaticsActual
Two identical conducting balls A and B have positive charges q₁ and q₂ respectively. But q₁ q₂ . The balls are brought together so that they touch each other and then kept in their original positions. The force between them is
Options
- Aless than that before the balls touched
- Bgreater than that before the balls touched
- Csame as that before the balls touched
- Dzero
Correct answer
B. greater than that before the balls touched
Step-by-step solution
According to coulomb's law, the force of repulsion between them is given by F= q₁ q₂ 4 ₀ r^2 When the charged spheres A and B are brought in contact, each sphere will attain equal charge q^ q^ = q₁+q₂ 2 Now, the force of repulsion between them at the same distance r is F^ = q^ q^ 4 ₀ r^2 = 1 4 ₀ ( q₁+q₂ 2 ) ( q₁+q₂ 2 ) r^2 = ( q₁+q₂ 2 )^2 4 ₀ r^2 As ( q₁+q₂ 2 )^2 q₁ q₂ F^ F