COMEDK20269 May 2026Morning ShiftPhysicsElectrostaticsActual
Two conducting spherical shells A and B of radii 4 cm and 6 cm respectively are placed with their centres 17 cm apart in air. Initially, sphere A was given a -20 nC charge while sphere B was uncharged. The spheres are then connected by a long thin conducting wire and allowed to reach electrostatic equilibrium. Assuming no charge is lost to the surroundings, the final charge on sphere A and the ratio of magnitude of e
Options
- A-12 nC ; 3 2
- B-8 nC ; 3 2
- C-8 nC ; 2 3
- D-12 nC ; 2 3
Correct answer
C. -8 nC ; 2 3
Step-by-step solution
When the two conducting spheres are connected by a long thin conducting wire, charge flows until their electrostatic potentials become equal. Assuming the distance between them is sufficient to ignore mutual potential effects, the potential of each sphere is given by V = kq R . Equating the potentials of sphere A and sphere B: V_A = V_B k q_A R_A = k q_B R_B q_A 4 = q_B 6 q_B = 3 2 q_A According to the conservation of charge, the total initial charge equals the total final charge: q_A + q_B = -20 nC q_A + 3 2 q_A =