Chapter 7, Problem 7.158IME

Interpretation Introduction

Interpretation:

The heat energy in the form of infrared radiation which is ineffective for photosynthesis should be explained using the concept of electromagnetic radiation.

Concept Introduction:

Electromagnetic spectrum is all forms of electromagnetic radiation where the only difference in radiation types is their wavelengths and frequencies.  Electromagnetic radiation can also be characterized by the number of waves per unit length.  This is termed as wave number, $\text{ν}$.

Figure.1

Electromagnetic energy is used to illustrate all different kinds of energies released into space by stars and the sun.  Although all electromagnetic radiation comes from the sun, ozone layer stops ultraviolet radiation from getting to the human beings.  The different waves are radio waves, TV waves, microwaves, infrared, ultraviolet waves, X-rays, gamma rays and cosmic rays.

Radio waves which are emitted by large antennas have long wavelengths and low frequencies.  They are used in broadcasting stations.  The visible light waves are produced by the motions of electrons within atoms.  The gamma rays ($\text{γ}$) which result from nuclear processes have short wavelengths and high frequencies.  The ultraviolet radiation, X-rays and $\text{γ}$-rays are high-energy radiation whereas infrared radiation, microwave radiation and radio waves are low-energy radiation.

The types of electromagnetic radiation which starts with the radiation having the longest wavelength and ends with the radiation having the shortest wavelength are given in the following order:

Radio waves, microwave, infrared, visible, ultraviolet, X rays, gamma rays