CBSE NOTES CLASS 12 PHYSICS
CHAPTER 8 ELECTROMAGNETIC WAVES
Nature of electromagnetic waves
Electromagnetic waves are combination of oscillating magnetic and electrical fields which are mutually perpendicular to each other and also perpendicular to the propagation of the wave. Electric and magnetic field vectors change sinusoidally.
If the propagation of wave is taken to be in z direction, Electrical field along x direction and Magnetic field along y directions, then the equation of plane progressive electromagnetic wave can be written as
Here ω =2πν is the angular frequency and k = is the magnitude of the wave vector (or propagation vector) . Direction of describes the direction of propagation of the wave.
We can see that speed of propagation of the wave is
The magnitude of the electric and the magnetic fields in an electromagnetic wave are related as
Where Eo and Bo are maximum values of electric and magnetic field vectors.