2.1 Introduction
2.2 Generation of Electromagnetic Waves
2.2.1 Speed of Electromagnetic Waves
2.2.2 Direction of Propagation of Electromagnetic Waves
2.2.3 Doppler Effect of Electromagnetic Waves
2.3 The Electromagnetic Spectrum
2.4.1 Energy Carried by Electromagnetic Waves
2.4.2 Radiation Pressure
2. Summary
Unit 2 - Multiple Choice - Electromagnetic Waves Questions
Unit 2 - Multiple Choice - Electromagnetic Waves Answers
Unit 2.1 Multiple Choice Extended Questions - Waves
Unit 2.1 Multiple Choice Extended Answers-Waves

Unit 2 Electromagnetic Waves


Electromagnetic Waves
An electromagnetic wave consists of oscillating electric and magnetic fields. An electromagnetic wave traveling along an x axis has an electric field and a magnetic field with magnitudes that depend on x and t:
E = Em sin(kx - ωt) and B = Bm sin(kx - ωt) where Em and Bm are the amplitudes of and E and B.
The electric field induces the magnetic field and vice versa.
The speed of any electromagnetic wave in vacuum is c = [E/B] where E and B are the simultaneous magnitudes of the fields.
The various possible frequencies of electromagnetic waves form a spectrum, a small part of which is visible light.


Energy Flow
The intensity of the waves at distance r from a point source of power is I = [Ps/4πr2].

Radiation Pressure
When a surface intercepts electro magnetic radiation, a force and a pressure are exerted on the surface. If the radiation is totally absorbed by the surface, the force is F = [IA/c] for total absorption and F = [2IA/c] for total reflection.
The radiation pressure (force per unit area) pr = [I/c] for total absorption and pr = [2I/c] for total reflection.

Electromagnetic waves are polarized if their electric field vectors are all in a single plane, called the plane of oscillation. Light waves from common sources are not polarized; that is, they are unpolarized, or polarized randomly.

Concept by Kishore Lal. Programmed by Kishore Lal... Copyright © 2015 Kishore Lal. All rights reserved.