1. What is Coulomb's Constant?

Coulomb's constant (k) is a proportionality constant in Coulomb's law that relates the electrostatic force between two point charges to the product of their charges and the inverse square of the distance between them.

2. Physical Significance

Coulomb's constant represents the electric force between two 1-coulomb charges separated by 1 meter in a vacuum. It connects the electrostatic force to the charges and distance in Coulomb's law.

3. Calculation Formula

Where:

• \( \varepsilon_0 \) — Vacuum permittivity (≈ 8.854 × 10⁻¹² F/m)
• \( \pi \) — Pi (≈ 3.14159)

4. Applications

Details: Coulomb's constant is fundamental in electrostatics, used in calculating:

• Electric force between charged particles
• Electric field calculations
• Electrostatic potential energy
• Capacitance calculations

5. Frequently Asked Questions (FAQ)

Q1: Why is the approximate value 9 × 10⁹ commonly used?
A: The approximation simplifies calculations while maintaining reasonable accuracy for most practical purposes.

Q2: How is Coulomb's constant related to the speed of light?
A: It's connected through the relationship \( k = \frac{1}{\varepsilon_0 \mu_0 c^2} \), where μ₀ is the vacuum permeability and c is the speed of light.

Q3: Does Coulomb's constant change in different media?
A: Yes, in materials other than vacuum, the effective constant is reduced by the relative permittivity (dielectric constant) of the medium.

Q4: Why does Coulomb's constant have such a large value?
A: The large numerical value compensates for the typically small magnitudes of elementary charges and the inverse square law's rapid decrease with distance.

Q5: How was Coulomb's constant first determined?
A: Through careful measurements of electrostatic forces between known charges at measured distances, originally by Charles-Augustin de Coulomb using a torsion balance.