From Coulomb's law, force between them F=r2KQ2 ....(1)
Step 2: Distribution of charges
When an identical uncharged spherical conductor A is brought in contact with charged sphere B.
By symmetry, the total charge will be shared equally among them, as both have equal radii.
∴ Charge on A and B =2Q
Now, when the conductor A is brought in contact with C.
They will also share equal charge among themselves, as both have equal radii.
∴ Charge on A and C =2Q+2Q=43Q
Step 3: Calculation of new force
New coulomb force between B and C:
F′=r2K2Q×43Q=83r2KQ2
From equation (1), we get: F′=83F
Hence, Option D is correct