Emissivity meaning, synonyms, antonyms, translation, and use cases

Emissivity

In today’s word for the day, we will be giving you highlight on the meaning of emissivity, its synonyms, antonyms, translation, and use cases.

Meaning

Emissivity is defined as the ratio of energy emitted from a material’s surface to that emitted from a blackbody, a perfect emitter with the same temperature, wavelength, and viewing conditions. It is an arbitrary number without dimensions between 0 (for an ideal reflector) and 1. (For a perfect emitter).

It is the efficiency of a surface in emitting energy as thermal radiation (electromagnetic radiation with wavelength depending on the temperature).

In addition to the material, a surface emissive also depends on the type of surface. In contrast to a roughened and oxidized metal surface, which will have a high emissivities, a clean and polished metal surface will have a low emissivities. Along with wavelength and angle, the surface’s temperature affects the emissivity.

Both reliable non-contact temperature measurement and heat transfer calculations require an understanding of surface emissive. Radiation thermometers pick thermal radiation released by a surface up. Typically, they are calibrated with blackbody reference sources whose emissive is as close to 1 as it is practically irrelevant.

 

Emissivity formula

It is determined by dividing the body temperature’s emissive power by the emissive power of a black object at the same temperature.

M = ε σ T 4
M = Total energy emitted from the surface of a material
ε = Emissivity
σ = Stefan-Boltzmann constant
T = Temperature of the emitting material in Kelvin

Thermal sensors gauge an object’s radiative temperatures. If the emissivities of the object is known, the radiant temperature can be used to estimate the true kinetic temperature of the object.

 

Synonyms

  • Emittance
  • Decarbonisation
  • Emissivities

 

Antonyms

  • Low- emissivity
  • Reflectivity

 

Translation

Spanish- emisividad
Latin- Emissio
Greek- Εκπομπή
French- Emissivité
Portuguese- Emissividade

 

First Known Use

The first known use of this word was in 1880.

 

Use cases

  • For the infrared thermograph investigation, the sides of the copper specimen were painted black to increase its emissivity.
  • It is necessary to investigate the embedded energy of many glass sheets and low emissivity coatings.
  • We have divided each emissivity by the atom density and by the period of propagation in order to accurately compare the calculations for various atom densities.

 

Frequently Asked Question

High emissivity: What does that mean?

A substance with a high emissivities also has a high absorptance. Lower emissivities objects produce less light, but they also reflect or disperse more light.

What is the emissivity unit?

The electromagnetic radiation energy travelling inside a unit solid angle in the direction through a unit area at a unit time in a unit spectral range is used to calculate emissivities in the general situation. Ib,w(T) is expressed in units of W/(cm2micron).

What elements influence emissivity?

For most materials, emissivities will only change with temperature if the surface characteristics of the material change, such as when coatings tarnish or degrade, or for metals like aluminum where It is critically dependent on the structure of the oxide layer, which is highly temperature dependent.

Does emissivity change with color?

Compared to black-colored materials, white materials absorb less radiation. Therefore, regardless of the type of material, two materials that just differ in hue will have distinct emissivities.

 

Video explanation of Emissivity

This video will give you a further explanation of the meaning of emissivity.

Summary

Both reliable non-contact temperature measurement and heat transfer calculations require an understanding of surface emissivity.
It is a measurement of a surface’s capacity to radiate heat efficiently.

When describing a material’s optical characteristics, It is utilized to account for the quantity of energy emitted in comparison to an ideal blackbody.

 

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