Coulomb

Definition

Coulomb is the fundamental unit of electric charge in the International System of Units (SI). It is named after the French physicist Charles-Augustin de Coulomb, who pioneered the study of electrostatic forces and the inverse-square law of electricity. Coulomb is a crucial concept that underpins the understanding of electrical charges, conservation of charge, charge transfer, Coulomb's law, capacitors, dielectrics, and Ohm's law.

5 Must Know Facts For Your Next Test

1. One coulomb is defined as the amount of electric charge carried by a constant current of one ampere flowing for one second.
2. The conservation of charge is a fundamental principle that states the total electric charge in an isolated system is constant and cannot be created or destroyed.
3. Coulomb's law describes the force between two point charges and is inversely proportional to the square of the distance between them.
4. Capacitors store electric charge and the amount of charge they can hold is measured in coulombs, with the capacitance measured in farads.
5. Ohm's law states that the current through a conductor is directly proportional to the voltage applied across it, and the proportionality constant is the resistance, measured in ohms.

Review Questions

• Explain how the concept of coulomb is related to the conservation of charge and the transfer of charge.
  • The coulomb, as the fundamental unit of electric charge, is central to the understanding of the conservation of charge and the transfer of charge. The conservation of charge states that the total electric charge in an isolated system is constant and cannot be created or destroyed. This means that the total number of coulombs in a closed system remains the same, even as charge is transferred from one object to another. The transfer of charge, such as through static electricity or electrical currents, involves the movement of coulombs of charge from one location to another, adhering to the principle of conservation of charge.
• Describe how Coulomb's law relates the electric force between two point charges to their charges and the distance between them.
  • Coulomb's law states that the electric 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. Mathematically, this can be expressed as $F = k \frac{q_1 q_2}{r^2}$, where $F$ is the electric force, $q_1$ and $q_2$ are the charges of the two objects, $r$ is the distance between them, and $k$ is the Coulomb constant. This relationship is fundamental to understanding how the coulomb, as the unit of electric charge, determines the magnitude of the electrostatic force between charged objects.
• Analyze the role of coulomb in the context of capacitors and dielectrics, and how it relates to Ohm's law.
  • The coulomb is a crucial concept in the study of capacitors and dielectrics. Capacitors store electric charge, and the amount of charge they can hold is measured in coulombs, with the capacitance measured in farads. The presence of a dielectric material between the plates of a capacitor affects the amount of charge that can be stored, as it alters the electric field and the relationship between the voltage and the charge. Additionally, Ohm's law, which states that the current through a conductor is directly proportional to the voltage applied across it, involves the movement of coulombs of charge through the conductor. The resistance, measured in ohms, determines the relationship between the voltage, current, and the flow of charge in coulombs.

Related terms

Electric Charge:

The fundamental property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be positive or negative, and it is the source of all electrical phenomena.

Electrostatic Force:

The force exerted between two stationary electric charges, which can be attractive or repulsive, and is described by Coulomb's law.

Electric Field:

The region around a charged particle or object where other charged particles experience a force. The electric field is a vector quantity, with both magnitude and direction.