The law of force between two charges is given by . . . . .

Answer

To solve the question regarding the law of force between two charges, we will refer to Coulomb's law, which describes the electrostatic interaction between charged particles.

### Step-by-Step Solution:

1. **Understanding the Charges**:
- We have two point charges, denoted as \( q_1 \) and \( q_2 \). These charges can either be positive or negative.

2. **Coulomb's Law**:
- The force \( F \) between these two charges is given by Coulomb's law, which states that the magnitude of the force is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance \( r \) between them.

3. **Mathematical Expression**:
- The formula for Coulomb's law can be expressed as:
\[ F = \frac{1}{4 \pi \epsilon_0} \frac{q_1 q_2}{r^2} \]
- Here, \( F \) is the magnitude of the force between the charges, \( \epsilon_0 \) is the permittivity of free space, and \( r \) is the distance between the centers of the two charges.

4. **Direction of the Force**:
- The direction of the force depends on the nature of the charges:
- If both charges are of the same sign (both positive or both negative), they repel each other.
- If the charges are of opposite signs, they attract each other.

5. **Conclusion**:
- Thus, the law of force between two charges is encapsulated in Coulomb's law, which provides both the magnitude and the direction of the electrostatic force acting between the charges.