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Definition of radiant energy: characteristics, types and examples

Definition of radiant energy: characteristics, types and examples

Radiant energy is a form of electromagnetic energy that includes visible light, radio waves, ultraviolet (UV) rays, etc. The main characteristic of this energy is that it can propagate in a vacuum without the need for any material support. In fact, radiant energy is a form of kinetic energy created when electromagnetic waves travel through space.

In this way, solar energy is the energy that travels in a straight line through space to reach Earth in the form of electromagnetic waves.

The SI unit of radiant energy is the joule (J).

Types of radiant energy

There are different types of radiant energies. Here are the most important ones:

  • Visible light is the part of radiant energy that the human eye can perceive. Light can be defined in terms of packets of small units called photons.

  • X-rays have electromagnetic waves that can pass through opaque bodies and print photographs. In medicine, they are used to make x-rays to diagnose diseases.

  • Gamma rays are generally produced by radioactive elements, by subatomic processes, or in some astrophysical phenomena. Gamma rays can damage the nucleus of cells.

  • Infrared rays are generated by electromagnetic radiation emitted by a body due to its temperature.

The higher frequency of these kinds of energy, the higher their energy.

Characteristics of radiant energy

Radiant energy is a form of energy transported through units called photons. A photon is an elementary particle that has no mass.

Another view of electromagnetic radiation is the presence of electromagnetic waves that carry energy in oscillating electric and magnetic fields. 

Suppose electromagnetic waves strike an object and are absorbed by the object. In that case, this energy is converted into heat (for example, in a solar thermal collector) or electrical energy (for example, in a photovoltaic PV panel).

Radiant energy can travel through a vacuum at the speed of light.

What is the primary source of radiant energy?

The primary source of radiant energy that reaches the Earth is solar radiation. This type of radiant energy is generated in the Sun due to nuclear fusion reactions that occur in its core.

When solar radiation reaches the Earth, part of the energy is absorbed by the planet, heating the Earth's surface. A percentage of the energy that comes to the surface is bounced back and re-emitted as wavelength electromagnetic radiation. Finally, part of the bounced energy does not get through the Earth's atmosphere because the greenhouse gases can absorb them.

Radiant energy examples

Here are some examples of different forms of radiant energy:

  • The energy emitted by the Sun and stars.

  • The heat emitted by a flame that is provoked by a fire.

  • A wireless network sends information using packets of energy.

  • A radiology machine for medical diagnostic purposes.

  • The action of heating food using a microwave oven.

  • The body generates heat, and it is capable of absorbing radiant energy.

  • The radioactivity of nuclear waste from an atomic power station.

  • The light energy and heat emitted by a light bulb.

  • The radiator of a house in operation.

Publication Date: April 21, 2022
Last Revision: April 21, 2022