8.1.A—Describe the electric force that results from the interactions between charged objects or systems

Describe the electric force that results from the interactions between charged objects or systems.

• Charge is a fundamental property of all matter.
  • i. Charge is a scalar quantity and is described as positive or negative.
  • ii. The magnitude of the charge of a single electron or proton, the elementary charge e, can be considered to be the smallest indivisible amount of charge.
  • iii. The charge of an electron is −e and the charge of a proton is +e, and a neutron has no electric charge.
  • iv. A point charge is a model in which the physical size of a charged object or system is negligible in the context of the situation being analyzed.
• Coulomb’s law describes the electrostatic force between two charged objects as directly proportional to the magnitude of each of the charges and inversely proportional to the square of the distance between the objects. Relevant equation:
• The direction of the electrostatic force depends on the signs of the charges of the interacting objects and is along the line of separation between the objects.
  • i. Two objects with charges of the same sign exert repulsive forces on each other.
  • ii. Two objects with charges of opposite signs exert attractive forces on each other.
• Electric forces are responsible for some of the macroscopic properties of objects in everyday experiences. However, the large number of particle interactions that occur make it more convenient to treat everyday forces in terms of nonfundamental forces called contact forces, such as normal force, friction, and tension.