Electromagnetism

• Electromagnetism can be defined (for our purposes here at lightcolourvision.org) as the field of physics that studies light in terms of the interconnections between electromagnetic force, electromagnetic fields, electromagnetic radiation and matter.
  • • Light is electromagnetic radiation and must be thought of as both a wave and a particle.
    • The electromagnetic spectrum includes all forms of electromagnetic radiation, from radio waves, through visible light to gamma rays.
    • Visible light is the kind of electromagnetic radiation our eyes respond to.
• It is the electromagnetic force that creates electromagnetic radiation. As the electromagnetic force pushes and pulls particles of matter it produces photons of light, little sparks of energy that can affect events within an atom or propagate across the universe. At a micro-scale, it is this pushing and pulling that binds electrons to atoms, maintaining molecular cohesion and so holding matter together.
• As a photon, a spark of electromagnetic energy is emitted at its source, it produces an electric and magnetic field around it as it propagates through space.
• Electromagnetic fields and photons are inextricably linked. The electromagnetic field is a manifestation of the photon’s presence, and the photon is the fundamental entity that gives rise to its component electric and magnetic fields.
• Electromagnetic fields shape the world through their effects on matter. For example, light can be absorbed by matter to produce heat, and, when light is given off by matter and reaches the retina of our eyes it enables us to see the world around us.
• Matter is anything that has mass and takes up space. It is composed of atoms, which are the smallest unit of matter that can exist on its own and still retain the properties of the element it is made of. Atoms are held together by the electromagnetic force.
• To provide context to all this, you might like to see our definitions and explanations of:
  • Classical physics
  • Quantum physics
  • Standard Model
  • Particle physics.

Electromagnetic Fields

• Electromagnetism is mediated by electromagnetic fields, which are regions of space where electric and magnetic forces are present. These fields are created by the movement or presence of electrically charged particles. The electric field is generated by the presence of electric charges, while the magnetic field is generated by the movement of electric charges or by the presence of permanent magnets.

Electric Charges

• Electric charges are fundamental properties of matter that determine how particles interact with electromagnetic fields. There are two types of electric charges: positive and negative. Particles with the same type of charge repel each other, while particles with opposite charges attract each other.

Electricity

• Electricity is the flow of electric charges. When electric charges move, they create an electric current. Electric currents can be generated by a variety of sources, such as batteries, generators, and solar cells. Electricity is used in a wide variety of applications, including lighting, heating, and transportation.

Magnetism

• Magnetism is the force that arises between magnetic objects. Magnetic objects are composed of materials that have aligned magnetic dipoles, which are like tiny magnets. Magnetic fields can be generated by permanent magnets or by electric currents. Magnetism is used in a wide variety of applications, such as compasses, motors, and MRI machines.

Light

• Light is a form of electromagnetic radiation that travels at the speed of light. Light is made up of photons, which are quanta of electromagnetic energy. Light can be visible, invisible, or ultraviolet. Light is used in a wide variety of applications, including communication, illumination, and photography.

Chemical Bonding

• Chemical bonding is the force that holds atoms together in molecules. Chemical bonds are formed by the sharing or transfer of electrons between atoms. Electromagnetism is responsible for all types of chemical bonding, including ionic bonding, covalent bonding, and metallic bonding.