Electromagnetic radiation
The Sun is a huge source of energy about 150 million kilometre away. The heat of sun transfer by radiation that carries energy as electromagnetic waves. Solar radiation can be captured and turned into useful forms of energy by us.
Electromagnetic radiation is a transverse wave that propagates as both electrical and magnetic waves traveling in packets of energy called photons. Electromagnetic spectrum include Y-rays, x-rays, UV rays, visible light, infrared light, and radio waves.
Electromagnetic waves from low to high frequency are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
Electromagnetic waves from high to low wavelength are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Radio waves have low-frequency, high wave length and possess lowest energy and longest radio waves have wavelengths in range from 1 km to thousands of kms. They can be emitted and received through antennas, and pass through the atmosphere and most building materials.
Gamma rays are high-frequency wave of the spectrum and have the highest energies due to the shortest wavelengths, much smaller than an atomic nucleus. Gamma rays, X-rays, and extreme ultraviolet rays are called as ionizing radiation because their high energy content that can to ionize atoms, causing chemical reactions.
An electromagnetic wave is also created by accelerating charges or moving charges back and forth that produce oscillating electric and magnetic fields on mutually perpendicular direction.
Visible light spectrum
The visible light spectrum is the segment of the electromagnetic spectrum that the human eye can eye can detect wavelengths. It has wavelength from 380 to 700 nanometers. When full spectrum of visible light passed through a prism, the wavelengths separate into the colors of the rainbow because each color is a different wavelength. Violet has the shortest wavelength, at around 380 nanometers, and red has the longest wavelength, at around 700 nanometer.
Properties of electromagnetic waves
- Electromagnetic waves (light wave) do not require medium for the wave to travel through like sound waves.
- Electromagnetic wave carries no mass but carry energy.
- Electromagnetic wave has momentum, and can exert pressure.
- The energy carried by an electromagnetic wave is proportional to the frequency of the wave and inversely proportional of wavelength.
- The wavelength and frequency of the wave are connected via the speed of light:
It is called Planck’s equation.
Where,
E = the energy of the photon
h = Planck’s constant (6.62x10^-34 Js)
𝜈 = the frequency of the light
c = the speed of light in a vacuum
( 3x10^8 m/s )
λ = the wavelength of the light
