Properties of electromagnetic waves

(i)                  They are neutral.

(ii)                They propagate as transverse wave.

(iii)               They propagate with the velocity of light.

(iv)              They contain energy and momentum.

(v)                Their concept was introduced by Maxwell.

Following waves are not electromagnetic

 (i) Cathode rays (ii) Canal rays    (iii) α rays   (iv) β rays   (v) Sound wave (vi) Ultrasonic wave

Some Important Electromagnetic Waves

Electro-magnetic Waves	Discoverer	Wavelength range (in meter)	Frequency range
γ- Rays	Henry Becqueral	10⁻¹⁴ to 10⁻¹⁰	10²⁰ to 10¹⁸
X- rays	W. Rontgen	10⁻¹⁰ to 10⁻⁸	10¹⁸  to 10¹⁶
Ultra-violet rays	Ritter	10⁻⁸ to 10⁻⁷	10¹⁶  to 10¹⁴
Visible radiation	Newton	3.9 x 10⁻⁷ to 7.8 x 10⁻⁷	10¹⁴  to 10¹²
Infra-red rays	Hershel	7.8 x 10⁻⁷ to 7.8 x 10⁻³	10¹²  to 10¹⁰
Short radio waves or Hertz Hertzian waves	Heinrich	10⁻³ to 1	10¹⁰  to 10⁸
Long radio Waves	Marcony	1 to 10⁴	10⁸  to 10⁶

Note:  Electromagnetic waves of wavelength range 10⁻³ m to 10⁻² m are called microwaves.

Phase of vibration: Phase of vibration of a vibrating particle at any instant is the physical quantities which express the position as well as direction of motion of the particle at that instant with respect to its equilibrium (mean) position.

Amplitude: Amplitude is defined as the maximum displacement of the vibrating particle on either side from the equilibrium position.

Wavelength: Wavelength is the distance between any two nearest particle of the medium, vibrating in the same phase. It is denoted by the Greek letter lambda.

In transverse wave distance between two consecutive crests or through and in longitudinal wave, distance between two consecutive compressions or rarefaction is equal to wavelength.

 Relation Between wavelength, frequency and velocity of wave

Velocity of wave = frequency x wavelength or, Ʊ= nʵ