College Physics III – Thermodynamics, Electricity, and Magnetism
Definition
Electrostatic force is the force of attraction or repulsion between two charged objects. It is described by Coulomb's law and acts along the line joining the centers of two charges.
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Electrostatic force follows Coulomb's law, which states that the magnitude of the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
The electrostatic force can be either attractive or repulsive depending on whether the charges are opposite or like, respectively.
Mathematically, Coulomb's law is expressed as $F = k_e \frac{|q_1 q_2|}{r^2}$ where $k_e$ is Coulomb's constant ($8.9875 \times 10^9 \text{N} \cdot \text{m}^2/\text{C}^2$), $q_1$ and $q_2$ are the magnitudes of the charges, and $r$ is the distance between them.
Electrostatic forces are central to understanding electric fields, as a charged object creates an electric field that exerts a force on other charges within that field.
Superposition principle applies to electrostatic forces; when multiple charges are present, the total electrostatic force on any charge is the vector sum of forces exerted by each individual charge.
Review Questions
What determines whether electrostatic force will attract or repel two objects?
How does Coulomb's law mathematically describe electrostatic force?
Explain how superposition principle applies to electrostatic forces.
Related terms
Coulomb's Law: A fundamental principle stating that electrostatic force between two point charges is directly proportional to their charge magnitudes and inversely proportional to the square of their separation distance.
Electric Field: A region around a charged object where other charged objects experience an electrostatic force.
Coulomb's Constant: $k_e$, a value approximately equal to $8.9875 \times 10^9 \text{N} \cdot \text{m}^2/\text{C}^2$, used in calculating electrostatic forces.