What is Radiant Energy

Radiant energy is defined as the energy of the electromagnetic waves which is calculated by integrating radiant flux with respect to time and has SI unit as joule. Radiometry, heating and lighting are the different fields in which it is used. It is also used sometimes in the field of telecommunication. Radiant energy is used to refer to electromagnetic waves when the transmission of power from one location to another is considered. Stream of Photons is considered to be the electromagnetic radiations and hence the energy carried by these photons is the radiant energy. Electromagnetic radiation can also be defined as an electromagnetic wave which carries its energy in its oscillating electric and magnetic field.

Frequency Of EM Radiation And Intensity Of Radiant Energy:

The electromagnetic radiation has various frequencies as it is seen in the atomic spectra or as in blackbody radiation. In case of photon, the energy carried by the photon is directly proportional to its frequency but in case of electromagnetic wave the energy of a monochromatic wave is directly proportional to the intensity of the wave.  Thus, if two electromagnetic waves have same intensity but different frequencies than the wave having higher frequency will have less number of photon when compared to the one having lower frequency because the energy carried by each of the photon is very high.

The electromagnetic wave when absorbed by an object converts the energy of the radiation into heat and warms the object. The example for this is the sunlight which warms the object on which it irradiates. However, these waves can also be reflected or scattered which results in the redistribution of their energy. In an open system energy leaves or enters a system by the mechanism of radiant energy.


The radiant energy is used for heating generally generated by infrared lamps or naturally as in case of solar system where the solar energy is trapped and the energy in it is converted to heat water. It is also used to conventionally heat the building or rooms in which the warmth is felt due to heating of the objects in the room rather than the air. There are many other applications of radiant energy as in treatment and inspections, separation and sorting, telecommunication etc. These applications are based on the source of radiant energy which is detected by a detector and converted to one of the signals which is characteristics of the radiant energy according to the need of the application. Nikola Tesla was the first to devise one of the earliest wireless telephones using radiant energy and having transmitters and receivers whose resonance was matched to the same frequency to allow communication.

The electromagnetic waves have energy called the radiant energy which is used for different applications. Its SI unit of measurement is joule. The radiant energy is often used for the purpose of heating by converting the energy in the electromagnetic radiation into heat. It is also used in telecommunication. ydrI � t � � �� ogether to form a light isotope of helium. In reaction 3,  two deuteron combine to form a triton and a proton. All the above fusion reaction involves fusion of two lighter nuclei to form a larger nucleus with release of enormous amount of energy. The nuclear fusion reaction is hindered by Coulomb repulsion which prevents two positively charged nuclei from fusing. The height of this Coulomb barrier depends on the height of the radii of the two interacting nuclei. The temperature at which the proton is a proton gas gives enough energy to overcome the coulomb’s barrier.

Bulk matter must be used to produce nuclear fusion to generate useful amount of energy. The temperature of the material is increased so much that the particles have enough energy through their thermal motion to overcome the coulomb barrier and is known as thermonuclear fusion. However, for thermonuclear fusion to happen extreme conditions of temperature and pressure is required which is present only in the stars including Sun. Thus, the energy generation in stars takes place via thermonuclear fusion.

Eniwetok Atoll is the place at which the first thermonuclear reaction on Earth occurred on November 1, 1952. On this day USA exploded a fusion device, which generated energy equivalent to 10 million tons of TNT (1 ton of TNT releases 2.6 x 1022 MeV of energy). Since fusion reactors are the future power source, it is being pursued vigorously in many countries

In fusion, lighter nuclei combine to form a larger nucleus. Fusion of hydrogen nuclei into helium nuclei is the source of energy of all stars including our sun. It is now possible to create thermonuclear fusion in controlled nuclear reactors to produce energy.