Q and q both refer to electric charges in Coulomb's Law, but they represent different charges. Q represents the total charge of an object, while q represents the charge of a single point charge.
The strength of the electric force is directly proportional to both Q and q. As Q or q increases, the force between two charged objects also increases.
Yes, both Q and q can be negative in Coulomb's Law. A negative Q or q indicates an object with a negative charge, which will result in an attractive force between two objects.
The electric force is inversely proportional to the square of the distance between two charged objects. As the distance increases, the force decreases.
No, Coulomb's Law can be applied to any two objects with electric charges, regardless of their size or shape. However, it is most accurate for point charges, which are small objects with evenly distributed charges.