• Angular momentum of EM waves can be understood in simple way. Consider a setup of · Part 2

around the conductor in which charge flows. If the charged Figure . Oscillating charges - sources of electromagnetic waves Propagation of an Electromagnetic Wave Source Direction of propagation Electric field vectors Magnetic field vectors Discharging spark or oscillating molecular dipole z x y 12th - 12th - - - - - Unit Electromagnetic waves . .

Electromagnetic spectrum Figure . Electromagnetic spectrum - Radio Microwave Wavelength Energy cm = , , nanometers .000000248 , , , . . .

, , electron volts , . . nanometers Infrared Visible light UV X-Ray Gamma Electromagnetic spectrum is an orderly distribution of electromagnetic waves in terms of wavelength or frequency (Figure . ).

Radio waves They are produced by accelerated motion of charges in conducting wires. The frequency range is from a few Hz to Hz. They show reflection and diffraction. They are used in radio and television communication systems and also in cellular phones to transmit voice communication in the ultra high frequency band.

Microwaves It is produced by special vacuum tubes such as klystron, magnetron and gunndiode. The frequency range of microwaves is Hz to Hz.These waves undergo reflection and can be polarised. It is used in radar system for aircraft navigation, speed of the vehicle, microwave oven for cooking and very long distance wireless communication through satellites. Infrared radiation It is produced by hot bodies (also known as heat waves) and also by when the molecules undergoing rotational and vibrational transitions.

The frequency range is Hz to × Hz. It provides electrical energy to satellites by means of solar cells. It is used to produce wave and k  (unit vector, here it is called propagation vector) denotes the direction of propagation of electromagnetic wave. Note that both electric field and magnetic field oscillate with a frequency (frequency of electromagnetic wave) which is equal to the frequency of the source (here, oscillating charge is the source for the production of electromagnetic waves).

In free space or in vacuum, the ratio between E