1. The Starting Point: It all begins with a changing electric field. This change could be due to:
* Moving electric charges: A moving electron creates a changing electric field around it.
* A changing electric field itself: A varying electric field can cause another electric field to change.
2. The Magnetic Response: A changing electric field creates a changing magnetic field perpendicular to it. This is described by one of Maxwell's equations, specifically Faraday's Law of Induction.
3. The Cycle Continues: This changing magnetic field, in turn, creates a changing electric field perpendicular to it. This is governed by another of Maxwell's equations, Ampere's Law with Maxwell's addition.
4. Self-Perpetuation: These changing electric and magnetic fields keep generating each other, propagating outwards as a self-sustaining electromagnetic wave.
Key points to remember:
* Perpendicularity: The electric and magnetic fields are always perpendicular to each other and to the direction of wave propagation.
* No Medium Needed: Electromagnetic waves are unique because they can travel through a vacuum, unlike mechanical waves which require a medium.
* Speed of Light: All electromagnetic waves travel at the speed of light in a vacuum (approximately 299,792,458 meters per second).
Think of it like a ripple effect in a pond:
1. A stone dropped into the water creates a disturbance (the changing electric field).
2. This disturbance creates waves (the changing magnetic field) that spread out.
3. The spreading waves create more disturbances (the changing electric field), continuing the cycle.
This continuous interplay between the electric and magnetic fields is what creates an electromagnetic wave!
