In Coulomb's law, the variable \( Q \) typically represents the magnitudes of the electric charges involved in the interaction. Specifically, if there are two point charges, Coulomb's law describes the force \( F \) between them as:
\[ F = k \frac{|Q_1 Q_2|}{r^2} \]
where:
- \( F \) is the magnitude of the electric force between the charges,
- \( k \) is Coulomb's constant (approximately \( 8.99 \times 10^9 , \text{N m}^2/\text{C}^2 \)),
- \( Q_1 \) and \( Q_2 \) are the magnitudes of the two point charges,
- \( r \) is the distance between the centers of the two charges.
So in this equation, \( Q_1 \) and \( Q_2 \) represent the quantities of the two charges, and they can be either positive or negative, indicating the nature of the charge (like or unlike).