CBSE Class 12-science Answered
The ranges of electromagnetic waves are given below:
(a) g-rays = <10ˉ³ nm
(b) Microwaves = 0.1 m to 1 mm
(c) x-rays = 1 nm to 10ˉ³ nm
(d) Radio waves = >0.1 m
Electromagnetic waves in the order of their increasing wavelength are
(a) g-rays
(b) x-rays
(c) Microwaves
(d) Radio waves
Infrared waves are adjacent to the low frequency or long-wavelength end of the visible spectrum. They are produced by hot bodies and molecules.
Visible light from the atmosphere is absorbed by the Earth’s surface and radiated as infrared radiation which gets trapped by greenhouse gases such as carbon dioxide and water vapour. This is how infrared radiation also plays an important role in maintaining the Earth’s warmth.
The molecules of CO₂, NH₃ and water which are present in most materials absorb infrared waves. Due to this, the molecules heat and heat their surroundings. Hence, their thermal motion increases. Medical instruments, such as the infrared lamp which is used in physiotherapy, work on this principle.