The Electromagnetic radiations are a form of energy which are emitted and absorbed by the charged particles. These radiations exhibit the wave like behavior while it travels through the space. Electromagnetic waves have electric as well as magnetic field which are orthogonal to each other and also to the propagation of the waves.
These radiations composed of several types of waves in different wavelength and frequency regions. These frequencies and wavelength are described with the help of electromagnetic spectrum. The Electromagnetic spectrum categorizes waves with different frequencies and wavelength according to their wave characteristics, uses and applications.
The Electromagnetic spectrum is divided into several regions based on
different frequencies, wavelengths and their characteristics. The figure shown below shows the Electromagnetic Spectrum Diagram which consists of all the em waves with respect to the wavelength and frequencies.
The Regions of the Electromagnetic Spectrum are as follows:
waves are majorly used for communication. These radio waves are further
divided into several bands extending from extremely low frequency to
extremely high frequencies. Although different geography have different
notions for different frequencies but the entire band is commonly used
for communication worldwide.
These waves are
initially thought of no use, but with research it is now-a-days used
for several purposes. The initial use of the microwave is in long range
communication but with time it is also used for heating the food.
infrared wave lies between 300 GHz to 405 THz and hence the infrared
wavelength is in between 750 nm - 1 mm. The near infrared lies between
0.75-1.4 $\mu$m wavelength range of infrared region while the far infrared
lies between 15 - 1000 $\mu$m wavelength range of infrared region. Infrared spectrometers are generally used to study the Vibrational Spectra of molecules.
Visible light :
frequencies in this region can be sensed by our eyes and interpreted as
colors ranging from violet to red. With the violet having shorter
wavelength and higher frequency while the red color have higher
wavelength and shorter frequency.
Ultraviolet wave or rays :
The ultraviolet rays lie above the visible spectrum and are invisible to our eyes. These waves can be felt as sun burns.
The X-rays lie above the ultraviolet band and are produced by the sudden
stoppage of the high speed charged particle by the use of metal target
which absorbs these particles and hence the x-rays are emitted by such
Gamma rays :
The Gamma rays are of extremely
low wavelength and are produced by the radioactive decay of the
The Electromagnetic radiation spectrum consists of all the waves whether it
is waves with the sub meter wavelength or wavelength in excess of kilometers.
The Electromagnetic radiation spectrum consists of the following electromagnetic waves:
- Gamma ray
- Ultraviolet rays
- Visible rays
- Infrared rays
- Radio wave.
EM spectrum is discussed in the form of a chart depicting the
electromagnetic spectrum frequency, Electromagnetic Spectrum Energy, and
electromagnetic spectrum wavelength of each region of the EM Spectrum.
||Photon Energy (eV)
||Less than 0.01 nm
||more than 10 EHz
||100 kev - 300+ GeV
|X - ray
||0.01 - 10 nm
||30 EHz - 30 PHz
||120 eV - 120 keV
||10 nm - 400 nm
||30 PHz - 790 THz
||3 eV - 124 eV
||390 nm - 750 nm
||790 THz - 405 THz
||1.7 eV - 3.3 eV
||750 nm - 1 mm
||405 THz - 300 GHz
||1.24 meV -1.7 eV
||1 mm - 1 meter
||300 GHz - 300 MHz
||1.24 $\mu$ eV - 1.24 meV
||1 mm - km
||300 GHz - 3 Hz
||12.4 feV - 1.24 meV
In the above table the Electromagnetic Spectrum Energy of all the frequencies is given. The Electromagnetic Spectrum Energy is measured by :
E = hf
h = Planck constant,
f = Frequency of the radiation and
E = Energy of the radiation.
The Microwave region in the EM spectrum lies between 300 MHz
to 300 GHz
which roughly comprises of the UHF
bands of the radio waves. In
the older time the microwaves are defined as wave with the wavelength in
the range of micrometers.
In the below chart we will discuss different
bands in the microwave region of the EM spectrum given by the Royal
Society of Great Britain.
||1 to 2 GHz
||2 to 4 GHz
||4 to 8 GHz
||8 to 12 GHz
||12 to 18 GHz
||18 to 26.5 GHz
||26.5 to 40 GHz
||33 to 50 GHz
||40 to 60 GHz
||50 to 75 GHz
||60 to 90 GHz
||75 to 110 GHz
||90 to 140 GHz
||110 to 170 GHz
these bands are not exhaustive but are mostly used in the
communications these days also. There are several other organizations
which gives different bands as per the use. The organizations like ITU-T
divide the microwave band according to its use in long distance
communication. The microwaves like other EM waves are harmful for us.
The extended exposure to microwaves can cause cancer in human tissues.
It can also produces cataracts in our eyes.
The electromagnetic spectrum radio wave is shown in below figure.
can be seen from the above diagram the radio wave band is further
divided into the several bands depending upon their frequencies.
The Infrared region consists of three bands:
Near infrared region:
The near infrared region is nearer to the visible region and they doesn’t have thermal characteristics.
Mid infrared region:
These infrared is used in telecommunication, communication, thermal imaging etc.
Far infrared region:
These are used in understanding the infrared emission from the deep space celestial objects and bodies.
The UV region consists of wavelength above the visible region and the
natural source of these waves or rays is our Sun. The other sources of
UV wave are celestial bodies far from our planet.