Main Difference – Radiation vs Emission
Radiation and emission are two related terms. Radiation is the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles which cause ionization. Electromagnetic radiation is characterized by the wavelength. Emission is the production and discharge of something, especially gas or radiation. Emission can happen in different forms such as gas emissions, particle emissions, radiation, etc. The main difference between radiation and emission is that radiation is the process of carrying what is emitted whereas emission is the process of formation and release of something.
Key Areas Covered
1. What is Radiation
– Definition, Different Types, Examples
2. What is Emission
– Definition, Different Types
3. What is the Difference Between Radiation and Emission
– Comparison of Key Differences
Key Terms: Electromagnetic Waves, Emission, Gamma Radiation, Ionization, Penetration, Radiation, Radioactive Decay, Wavelength
What is Radiation
Radiation is the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles which cause ionization. Radiation can also be defined as the mode of traveling energy through space.
Radiation can occur via either waves or particles. Radiation can go through space as well as through some materials. There are two types of radiation as ionizing radiation and non-ionizing radiation. Ionizing radiation is radiation that carries enough energy to liberate electrons from atoms or molecules. This means ionizing radiation can ionize things. Non-ionizing radiation refers to any type of electromagnetic radiation that does not carry enough energy to ionize atoms or molecules. Therefore, nonionizing radiation cannot ionize things.
Details about some common forms of radiation are discussed below.
Alpha Radiation
Alpha radiation (α) is a type of ionizing radiation. Alpha radiation contains alpha particles. An alpha particle consists of two protons and two neutrons. Alpha radiation occurs when an atom undergoes radioactive decay. Due to the high mass and its electrical charge (+2), alpha particles strongly interact with matter. But it can go through the air only to a few centimeters and can easily be stopped by a thin material. Ex: alpha radiation cannot penetrate the skin.
Beta Radiation
Beta radiation (β) is a type of ionizing radiation that consists of either electrons or positrons. Both electrons and positrons are of similar mass but their electrical charges are opposite to each other. (Electrons are negatively charged, positrons are positively charged). Beta radiation can go through air up to several meters and it can penetrat the skin. But beta radiation can be stopped by a plastic or a piece of paper.
Gamma Radiation
Gamma radiation is a type of ionizing radiation. It is denoted by γ. It is a kind of penetrating radiation. That means it can penetrate most materials. This radiation is composed of photons with high energy. Sources of gamma radiation include radioactive decay of radioactive elements, thunderstorms, laboratory sources, etc. The wavelength of this radiation is less than 10 picometers.
Figure 1: Penetration of Materials by Alpha, Beta, and Gamma Radiation
X ray
X ray or X radiation is a type of ionizing radiation that can penetrate through some materials. But the strength of penetration is less than that of gamma radiation. These rays are used to get x ray radiographs in medical sciences. The wavelength of X radiation is 0.01 to 10 nm.
UV Light
UV light or ultraviolet light is a type of non-ionizing radiation. Although it is non-ionizing radiation, it is carcinogenic when skin and eye are exposed to UV light since this radiation can cause oxidations and mutations in tissues. The wavelength range is from 10 nm to 400 nm.
Visible Light
The wavelength of visible light is in the range 380–750 nm. This radiation is visible to human eye. What we get as sunlight is visible light radiation.
What is Emission
Emission is the production and discharge of something, especially gas or radiation. Therefore, emission may refer to the emission of a chemical compound, emission of electromagnetic radiation, etc.
When the emission of a chemical compound is considered, the chemical compound is a gas. This gas is a product of a certain chemical reaction. Gases are often emitted from automobiles, factories, etc. Most of these gases are air pollutants. Some examples include carbon dioxide (CO2), sulfur oxides, nitrogen oxides, carbon monoxide, volatile organic compounds, etc.
Figure 2: Propagation of an Electromagnetic Wave
When the emission of electromagnetic radiation is considered, the radiation is emitted in the form of photons. Electromagnetic radiation is created when a charged subatomic particle is accelerated by an electric field. This results in a movement of the subatomic particle. This movement causes the creation of electric and magnetic waves that are perpendicular to each other. This combination is what we call an electromagnetic wave. The energy of these waves is carried by energy bundles known as photons that have a zero mass.
There are many applications of these emissions. For example, emission spectra of atoms give details required to understand the atomic structure. Other types of radiation include UV radiation, visible light, gamma radiation, X radiation, etc.
When particle emission is considered, particles are emitted by radioactive materials during their radioactive decay. These particles are emitted in the form of radiation. Particle emissions can be alpha particles, beta particles, gamma particles, etc.
Difference Between Radiation and Emission
Definition
Radiation: Radiation is the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles which cause ionization.
Emission: Emission is the production and discharge of something, especially gas or radiation.
Process
Radiation: Radiation is the process of movement of what is emitted through space or material.
Emission: Emission is the production and releasing of something.
Different Forms
Radiation: Different forms of radiation include gamma radiation, alpha radiation, beta radiation, X-ray, visible light, etc.
Emission: Different forms of emission include gas emissions, radiation emissions, etc.
Sources
Radiation: Sources of radiation include radioactive decay of radioactive elements, thunderstorms, laboratory sources, etc.
Emission: Sources of emission include automobiles, factories, radioactive elements, etc.
Conclusion
Radiation is the emission of electromagnetic waves. But emission can be either electromagnetic waves, particles or gases. The main difference between radiation and emission is that radiation is the process of carrying what is emitted whereas emission is the process of formation and release of something.
References:
1. “What is Radiation.”- World Nuclear Association, Available here.
2. “Radiation.” Wikipedia, Wikimedia Foundation, 26 Sept. 2017, Available here.
3. “Air pollution.” Wikipedia, Wikimedia Foundation, 13 Dec. 2017, Available here.
Image Courtesy:
1. “Alfa beta gamma neutron radiation” By Image:Alfa_beta_gamma_radiation.svg – Image:Alfa_beta_gamma_radiation.svg (GFDL) via Commons Wikimedia
2. “Electromagneticwave3D” By By Lookang many thanks to Fu-Kwun Hwang and author of Easy Java Simulation = Francisco Esquembre – Own work (CC BY-SA 3.0) via Commons Wikimedia
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