Answer:

Step-by-step explanation:
Data provided:
Charge on the glass rod, Q = 0.680 μC = 0.680 × 10⁻⁶ C
Charge on the silk cloth, q = 0.590 μC = - 0.590 × 10⁻⁶ C
Distance between glass rod and the silk cloth, r = 11.0 cm = 0.11 m
now,
The force between (F) the charges is given as:

where,
k is the Coulomb's constant = 9 × 10⁹ N.m²/C²
on substituting the respective values, we get

or
