Advanced Physics → Fields, Waves & Optics → Electromagnetic Fields
Electromagnetic fields describe how charges interact across space without direct contact.
1. What Is a Field?
A field assigns a physical quantity to every point in space. In electromagnetism, fields replace the idea of action at a distance.
2. Electric Fields
An electric field exists around every electric charge. It determines the force experienced by other charges placed in that region.
3. Magnetic Fields
Magnetic fields arise due to moving charges and electric currents. They exert forces only on moving charges.
4. Force on a Moving Charge
The force experienced by a charge moving in electric and magnetic fields depends on its velocity and the field configuration.
The electric part of the force can change the speed of the charge, while the magnetic part only bends its path because it is always perpendicular to the velocity.
5. Motion in Magnetic Fields
Magnetic forces change the direction of motion but not the speed. This leads to circular or helical trajectories.
6. Unification: Electromagnetic Fields
Electric and magnetic fields are not separate entities. They transform into each other depending on the observer’s frame of reference.
7. Why Electromagnetic Fields Matter
- They explain light and radiation
- They govern electronics and communication
- They unify electricity, magnetism, and optics