What is the Coulomb’s Law for?

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When evaluating what Coulomb’s Law is for, it helps to recall the core quantity it describes in electrostatics.
Option a: 'To measure electric fields between two charges' This is not the primary purpose of Coulomb’s Law. Electric fields are described by E = F/q, which relates the force to the field experienced by a test charge, not directly by Coulomb’s Law itself. Coulomb’s Law gives the force between charges, while Gauss’s law and field concepts handle fields more broadly. So this option confuses the force between charges with the field produced by them.
Option b: 'To measure electric potentials between two charges' Electric potential is a scalar quantity related to energy per unit charge and is derived from the work done by electric forces. While Coulomb’s Law can be used in derivations that lead to potential, the law itself is not the definition or primary tool for measuring potentials. This makes the option conceptually misleading.
Option c: 'To measure electric potential energy between two charges' Potential energy between charges can be computed from Coulomb’s Law by integrating the work required to assemble the charges, but Coulomb’s Law directly gives the force, not the potential energy itself. Therefore, this option captures only a derivative relationship, not the direct purpose of the law.
Option d: 'To measure electric forces between two charges' This statement aligns with the fundamental role of Coulomb’s Law: it provides the force magnitude and direction between two point charges as F = k * q1 * q2 / r^2 (with appropriate sign for direction). This is the direct, primary use of the law and what it was formulated to quantify. Hence, this option accurately describes the law’s purpose.
In summary, options a, b, and c misattribute or confuse the primary quantity described by Coulomb’s Law (force) with related but distinct concepts (fields, potentials, or energy). Option d correctly locates the law’s main purpose: computing the electric force between two charges.

UCIC 202503 PHYS101 Quiz 9

What is the Coulomb’s Law for?

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