Chapter: 11th Botany : Chapter 13 : Photosynthesis
Spectrum of ÂElectromagnetic Radiation
Spectrum of ÂElectromagnetic
Radiation
In the total electromagnetic spectrum,visible light is the smallest part. The entire life on earth depends on light and is the driving force for all organisms. Plants have natural potential to utilize solar energy directly. In the given picture electromagnetic radiation spectrum and components of visible spectrum are mentioned. The wavelength of solar radiation which reaches the earth is between 300 to 2600 nm. The visible spectrum ranges between 390 to 763 nm (3900 Ã… to 7630 Ã…). The colour of the light is determined by the wavelength. Energy of the quantum is inversely proportional to wavelength.
Shorter wavelength has more
energy than longer wavelength. Electromagnetic spectrum consists of 8 types of
radiations such as cosmic rays, gamma rays, X rays, U-V rays, Visible light
spectrum, infrared rays, electric rays and radio rays (Figure 13. 5).
Properties of Light
1)
Light is a transverse electromagnetic wave.
2)
It consists of oscillating electric and magnetic
fields that are perpendicular to each other and perpendicular to the direction
of propagation of the light.
3)
Light moves at a speed of 3 × 108 ms–1
4)
Wavelength is the distance between successive
crests of the wave.
5)
Light as a particle is called photon. Each photon contains an amount of energy known as quantum.
6)
The energy of a photon depends on the frequency of
the light (Figure 13. 6).
Related Topics