Electromagnetic force: properties

The electromagnetic force is evident at both very small and very large scales. At one extreme, it acts between electrons and photons within atoms, which are incredibly small distances. At the macro scale, it influences how life on Earth interacts with distant cosmic events.

  • The electromagnetic force acts between electrons and photons within atoms. Electrons are negatively charged particles, while photons are quanta of electromagnetic energy. The electromagnetic force mediates their interactions, enabling electrons to transition between energy levels and photons to be emitted or absorbed. The distances involved in atomic interactions are incredibly small on the order of angstroms (10^-10 meters).
  • The electromagnetic force is responsible for interactions between charged particles at macroscopic scales. For example, it governs the interactions between celestial bodies and life on Earth. The distances involved in such interactions can indeed be measured in light years. Examples include:
    • Human sight is enabled by the interaction of electromagnetic radiation with specialized cells in the retina of the eye called photoreceptors. These cells are sensitive to certain wavelengths of light, allowing us to perceive our surroundings. Our understanding of the world is heavily reliant on electromagnetic radiation (light), which allows us to observe and study both near and distant objects.
    • Photosynthesis is a crucial process for plants, algae, and some bacteria. It involves the conversion of electromagnetic energy (sunlight) into chemical energy in the form of glucose. Without light, there would be no life on Earth.
  • The properties listed below help to explain many of the phenomena associated with electromagnetic force, such as the behaviour of light, the formation of atoms and molecules, and the attraction between magnets.
  • Properties of the electromagnetic force include:
    • Charge: The electromagnetic force is only exerted between electrically charged particles. Particles with the same charge repel each other, while particles with opposite charges attract each other.
    • Direction: The electromagnetic force is a vector force, meaning that it has both magnitude and direction. The direction of the electromagnetic force is always along the line connecting the two charged particles.
    • Range: The electromagnetic force is a long-range force, meaning that it can act over large distances. However, the force between two charged particles decreases as the distance between them increases.
    • Strength: The electromagnetic force is the second strongest of the four fundamental forces. The order and relative strength of fundamental forces are:
      • Strong force (1)
      • Electromagnetic force (1/137)
      • Weak force (10-6)
      • Gravity (10-37)
    • Universality: The electromagnetic force is universal, meaning that it acts on all electrically charged particles in the same way, regardless of their mass or composition.