What is radiation?

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steveschoen | College Teacher | (Level 1) Associate Educator

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Radiation is a type of heat transfer.

There are three types of heat transfer: radiation, convection, and conduction.

Conduction is the transfer of heat between objects that are in direct contact with each other.  An example would be when the end of a metal rod is heated.  The heat would "transfer down" the metal rod to the cooler end, ending up being distributed throughout the metal rod.  The "transferring down" is the conduction.

Convection occurs when there is transfer of heat between hot and cold places.  A good example of this is the atmosphere.  The sun warms the air.  The warmer air rises, and the cooler air sinks down.  The warm air rising and cool air sinking is the convection.

With convection and conduction, heat is transferred to an object by an outside source.  With radiation, no outside heat source is needed.  The object generates its own heat.  And, that heat can even be generated in a vacuum.  Example of radiation is the sun, which is in outer space (a vacuum).  Another example would be the heat given off by the filament in a light bulb.

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atsuzuki's profile pic

atsuzuki | (Level 1) Adjunct Educator

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A short answer to this question is that radiation is anything that radiates or is emitted from a source. In general, it refers to either waves (sound, electromagnetic, etc.) or particles (alfa particle, beta particle, etc.) that emanates from some source. Since the emanated thing (waves or particles) carry energy, it can be said that radiation is the emittance of energy from that source. Heat, of course, is a type of energy and radiation also refers to a type of possible heat transfer.   

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sciftw | High School Teacher | (Level 1) Educator Emeritus

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Any emission of light from an electrically charged particle (electron).  You might be able to see it, you might now.  It all depends on the frequency of the emission.  You can see visible light radiation.  It comes in red, orange, yellow, green, blue, indigo, and violet.  Too low of frequency, you can see, but can experience as infrared heat, microwave radiation, or radio radiation.  Too high and you know that as ultraviolet, x-ray, and gamma radiation.  Most radiation is completely harmless too humans.  People freak out about the word "radiation" because they are thinking of gamma, which would be associated with cancer treatment . . . or creating Marvel super heroes. 

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ssarfraz | Student, Professional | (Level 2) Honors

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Radiation

Transmission of electromagnetic waves in the form of rays and particles, is known as Radiation.

Types of Radiation are divided under two major categories:-

  • Ionizing Radiation
  • Non-ionizing Radiation

Ionizing Radiation examples are as follows:-

  1. X rays
  2. Y rays

Non-Ionizing Radiation examples are as follows:-

  1. Light
  2. Sound
  3. Heat
  4. Radio waves
  5. Microwaves
  6. Infrared Waves
  7. Ultraviolet Waves
  8. Mobile devices
  9. Radar
  10. TV

Kinds of Radiation:-

  1. Alpha Radiation
  2. Beta Radiation
  3. Gamma & X rays
  4. Neutrons
  5. Aluminum
  6. Lead
  7. Concrete

Radiation - Heat Transfer

Transfer of energyacross a system bounded by means of an electromagnetic mechanism that is caused solely by a temperature difference.

Types are as follows:-

  1. Electromagnetic Radiation: Radiations that are produced by vibrational and rotational movements of atoms and molecules.
  2. Thermal Radiation: Change in the atomic energy levels that are indicated by temperature.

Sources of radiation in everyday life (Given in percentage)

  1. Natural Sources
  2. Artificial / Man made sources

Natural Sources (85%) are divided as follows:-

  • Buildings / Soil                              18%
  • Cosmic                                         14%
  • Radon                                          42%
  • Food/Drink - Water                       11%

Artificial Sources (15%) are as follows:-

  • Medicine                                       14%
  • Nuclear industry                             1%

Uses of radiation:-

Radiation is a part of our daily life. We can benefit from it if used properly. The uses are divided into these categories:-

  1. Electricity generation
  2. Medical applications
  3. Industrial applications
  4. Agricultural applications
  5. Applications in consumer products
  6. Archeological applications

Effects of Radiation on human body are as follows:-

  • Massive cell death
  • Development of cancer
  • Development of gene mutations
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rachellopez | Student, Grade 12 | (Level 1) Valedictorian

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According to Health Physics Society, radiation is "energy that comes from a source and travels through space and may be able to penetrate various materials". Basically, radiation is just electro-magnetic waves.

There are different types of radiation including ionizing, cosmic, and non-ionizing radiation. With different fields, radiation is used/studied in different ways. In the medical field, for example, radiation treatments are used to kill cancer.  

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udonbutterfly | Student, College Freshman | (Level 1) Valedictorian

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Radiation can be described differently in other terms in science. For example radiation in context of light can be describes as the emission of different types of particles like x-ray and infrared rays. Then there is also radiation in the context of nuclear chemistry where it can be divided into alpha, beta, and gamma.

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sid-sarfraz | Student, Graduate | (Level 2) Salutatorian

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Radiation is the transmission of particles or electromagnetic waves in air. Radiation of waves in form of light, heat etc do not need any medium to travel through. These are waves that can be felt and not touched. Like heat of fire, that can be used to warm up the hands but cannot be touched. 

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malkaam | Student, Undergraduate | (Level 1) Valedictorian

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Radiation is mainly infrared. It is part of the electromagnetic spectrum, possessing wavelengths between those of radio waves and those of visible light. Radiation can travel at the speed of light through the vacuum. it can also travel through air. Radiation is the heat transfer which does not need a material medium, it travels mainly as electromagnetic waves.

Example is Solar energy, which is the energy received from the sun through radiation, it can pass through a vacuum. 

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zumba96 | Student, Grade 11 | (Level 3) Valedictorian

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There are two types of radiation. One for physics and one for biology. In physics it can relate to the emission of energy when electromagnetic waves or high energy particles cause ionization. 

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parama9000 | Student, Grade 11 | (Level 1) Valedictorian

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Radiation may refer to one of the three methods of heat transfer:

Convection

Conduction

and Radiation

or it could refer to the emission of energy as electromagnetic waves, or simply the branching out from a central point.

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parama9000 | Student, Grade 11 | (Level 1) Valedictorian

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Radiation may refer to one of the three forms of heat transfer: convection, conduction and radiation.

Alternatively, it can refer to the emission of energy as electromagnetic waves or moving subatomic particles or the divergence out from a central point, in particular evolution as per the dictionary definition.

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musiclover17 | Student, Grade 6 | (Level 1) eNoter

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1.
Physics
the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization.
 
  • 2.
    Biology
    divergence out from a central point, in particular evolution from an ancestral animal or plant group into a variety of new forms.
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bchandra1955 | eNotes Newbie

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By radiation we mean emission of energy, and it can take place in the form of electromagnetic waves. The wavelength or frequency of electromagnetic waves define the nature of radiation and suitable filters need to be used if we need to safeguard certain life forms or equipments.

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