The coulomb electrostatic force is defined for

Options

A. two spherical charges at rest
B. two spherical charges in motion
C. two point charge in motion
D. two point charges at rest

Answer

To solve the question regarding the definition of the Coulomb electrostatic force, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Coulomb's Law**:
Coulomb's law describes the electrostatic force between two point charges. It states that the force (F) between two charges (q1 and q2) is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the distance (r) between them. The formula is given by:
\[ F = k \frac{|q_1 q_2|}{r^2} \]
where \( k \) is Coulomb's constant.

2. **Identifying the Nature of Charges**:
The question presents four options regarding the nature of the charges involved:
- Two spherical charges at rest
- Two spherical charges in motion
- Two point charges in motion
- Two point charges at rest

3. **Analyzing the Options**:
- **Spherical Charges at Rest**: While Coulomb's law can apply, it is generally more accurate for point charges.
- **Spherical Charges in Motion**: Coulomb's law does not apply as it is for static charges.
- **Point Charges in Motion**: Coulomb's law is not applicable as it is defined for static charges.
- **Point Charges at Rest**: This is the ideal scenario for applying Coulomb's law since it is designed for static point charges.

4. **Conclusion**:
Based on the analysis, the Coulomb electrostatic force is defined for **two point charges at rest**. Therefore, the correct answer is:
\[ \text{Option D: Two point charges at rest} \]