Electromagnetic spectrum - Jankari Store

Electromagnetic spectrum

In simple words the electromagnetic spectrum is defined as the range of all types of electromagnetic radiation.  It represents a continuum of electromagnetic radiations arranged on the basis of wavelength.  It ranges from shorter wavelengths (gamma rays to X-rays) to longer wavelengths (microwaves and radio waves).

The total range of wavelengths from a micrometer to a meter is commonly referred to as the electromagnetic spectrum. The electromagnetic spectrum (EMS) is divided into different regions that go from the shortest wavelength to the longer wavelength regions. We observe cosmic rays, gamma rays and X-rays. The UV region (0.27μm - 0.4 μm) is the first region in which sensors based on optical principles i.e. televisions, scanners and UV cameras in which films and filters can operate. Wavelengths less than 0.3 µm cannot reach the Earth's surface because it is absorbed by the ozone layer in the atmosphere. After the UV zone, it is the visible part of the spectrum, this region of the spectrum is usually the cause of light. It is the only part of the spectrum that is associated with the concept of color.

Electromagnetic spectrum regions and their characteristics.

1.) Gamma rays (wavelength <10-¹²)

• It has the shortest wavelength (less than 0.01 nanometer) and the highest energy of any region of EMS.

 • It is produced by the hottest objects in the universe including neutron stars, pulsars, supernova explosions.

 • It can also be made by nuclear explosion.

2.) X-rays (10-⁸ to 10-¹² meters)

• X-rays range in wavelength from 0.01 to 10 nanometers and originate mainly from superheated gas, exploding stars and quasars.

 • X rays are able to pass through many different types of materials.

 • These are commonly used for medical imaging and for inspection of cargo and baggage.

3.) Ultraviolet region

• This region lies beyond the violet region of the spectrum, with a wavelength of about 0.38 micrometers.

 • The rays from this region are the most harmful and are almost absorbed by our atmosphere.

4.) The visible spectrum

• It covers a range of wavelengths from 0.4 to 0.75 micrometers. This is the only region of the spectrum to which the human eye is sensitive.

 • This is the only part of a spectrum that says the colors blue green and red are the primary colors of the visible spectrum.

 • They are defined as such because no one primary color can be made from the other two, but all other colors can be made by mixing all three in different proportions.

 • Each individual wavelength is representative of a particular color within the visible spectrum.

 • The visible spectrum is used extensively in remote sensing and is the energy that is recorded using photography.

5.) Infrared region

• It ranges in wavelength from about 0.75 micrometers to 100 micrometers.

 •Its ​​wavelength is longer than the red part of the visible spectrum, the infrared region is divided into two categories based on their radiative properties.

 a.) Reflected infrared region (0.7 micrometer to 3 micrometer)

 b.) Thermal infrared region (3 micrometer to 100 micrometer)

6.) Microwave region 

•It ranges in wavelength from 1mm to 1m.

• These are high frequency waves used in remote sensing and satellite communication.

• The main advantage of this spectrum is its ability to penetrate through clouds, smoke, light rain and snow which are beneficial in satellite communications.

7.) Radio waves

•It has the longest wavelength in EMS with wavelengths ranging from about 1 mm to several hundred meters.

• They are used to transmit different types of data.

• Wireless networking, television and amateur radio all use radio waves.