This week in the Ron Paul Curriculum physics course was an introduction to electromagnetic waves and light.
Maxwell was the the Newton of electromagnetic. He created 4 equations or principles:
- A generalized equation that related electric field to its source.
- Electric charge law and a similar law for a magnetic field.
- An electric field is produced by a changing magnetic field.
- A magnetic field is produced by an electric current or a changing electric field.
App to EM waves:
Maxwell discovered that when you combine the 3rd and 4th equations that it produces a wave that propagates.
Production of EM waves:
We quickly went over EM wave diagrams and how they work
There is an electrical and magnetic component to electromagnetic fields:
- Permeability of free space: measure of the ability to form magnetic field in free space
- Permittivity of free space: the measure of how much resistance is encountered when forming an electric field
Speed of EM waves
A quick review of wave speed and wavelength:
Relationship between speed, frequency, and wavelength: v = f λ
For EM waves we let v = c: therefore c = f λ
Electromagnetic spectrum overview
Energy can be transmitted by EM waves
We know that electric and magnetic fields can hold energy, therefore is makes sense that EM waves can transmit energy.
Energy transmitted at any instant:
The equation gives instantaneous energy transported per unit area per unit time
Average energy transmitted: