Coulomb Law Electric Charge Force

Overview

Engineering reference data for Coulomb Law Electric Charge Force in electrical engineering.

Key Formulas

Ohm's Law

$V = IR$

Voltage = Current × Resistance.

Power

$P = VI = I^2R = V^2/R$

Electrical power.

Energy

$E = Pt$

Energy = Power × Time.

Variables

Worked Example

For two spheres in air with distance 20 mm (0.02 m), both carrying a charge of 2 μC, the electrostatic force is calculated as:

$$F = \frac{(8.98755 \times 10^9\ \text{N}\cdot\text{m}^2/\text{C}^2) \times (2 \times 10^{-6}\ \text{C}) \times (2 \times 10^{-6}\ \text{C})}{(0.02\ \text{m})^2} \approx 90\ \text{N}$$

Practical Charge Units

In practice, charge values are often expressed in multiples of the elementary charge $e = 1.602 \times 10^{-19}\ \text{C}$. The total charge $q$ on an object is quantized, meaning it exists as an integer multiple of $e$: $q = n e$ where $n$ is the number of electrons added (negative charge) or removed (positive charge).

Common unit conversions:

• $1\ \mu\text{C} = 10^{-6}\ \text{C}$
• $1\ \text{C}$ is equivalent to the charge of approximately $6.24 \times 10^{18}$ electrons.

References

• Original Source