Answer
Verified
389.1k+ views
Hint: Emissive power is the radiant energy emitted by the Body. Body should be anything either it is black or gray, coefficient of emission is the fractional part of power of a perfectly black Body at the same temperature.
Complete step by step answer:
Emissive power (E) of a material at a certain temperature is defined as the rate of radiation emitted through a unit area of the material.
or Emissive power is the power of a body at a given temperature emitted as radiant thermal energy from a unit surface area of a hot body per unit time. It is also known as spectral emissive power. Basically, it is the total amount of thermal energy emitted per unit area per unit time.
Let Q is the amount – of thermal energy emitted.
‘A' is the surface area of the body
‘t’ is the time for which body emits energy
Thus,
\[\text{Emissive power}=\dfrac{Q}{At}\]
SI unit of emissive power is watt per square meter\[\left( W/{{M}^{2}} \right)\]
Coefficient of emission of a body can be defined as the emissive power of a body to emissive power of perfect black body.
Hence, $\text{Emissivity(e)=}\dfrac{\text{rate}\,\text{of}\,\text{radiation}\,\text{emitted}\,\text{through}\,\text{a}\,\text{unit}\,\text{area}\,\text{of}\,\text{material}}{\text{rate}\,\text{of}\,\text{radiation}\,\text{emitted}\,\text{through}\,\text{a}\,\text{unit}\,\text{area}\,\text{of}\,\text{blackbody}}$
The object and the blackbody should be exposed in the same condition.
Note:
Emissive power a Body is the thermal Energy emitted per unit area per unit time and emissive coefficient is the ratio of emissive power of anybody to emissive power of a black body.
Complete step by step answer:
Emissive power (E) of a material at a certain temperature is defined as the rate of radiation emitted through a unit area of the material.
or Emissive power is the power of a body at a given temperature emitted as radiant thermal energy from a unit surface area of a hot body per unit time. It is also known as spectral emissive power. Basically, it is the total amount of thermal energy emitted per unit area per unit time.
Let Q is the amount – of thermal energy emitted.
‘A' is the surface area of the body
‘t’ is the time for which body emits energy
Thus,
\[\text{Emissive power}=\dfrac{Q}{At}\]
SI unit of emissive power is watt per square meter\[\left( W/{{M}^{2}} \right)\]
Coefficient of emission of a body can be defined as the emissive power of a body to emissive power of perfect black body.
Hence, $\text{Emissivity(e)=}\dfrac{\text{rate}\,\text{of}\,\text{radiation}\,\text{emitted}\,\text{through}\,\text{a}\,\text{unit}\,\text{area}\,\text{of}\,\text{material}}{\text{rate}\,\text{of}\,\text{radiation}\,\text{emitted}\,\text{through}\,\text{a}\,\text{unit}\,\text{area}\,\text{of}\,\text{blackbody}}$
The object and the blackbody should be exposed in the same condition.
Note:
Emissive power a Body is the thermal Energy emitted per unit area per unit time and emissive coefficient is the ratio of emissive power of anybody to emissive power of a black body.
Recently Updated Pages
Basicity of sulphurous acid and sulphuric acid are
Assertion The resistivity of a semiconductor increases class 13 physics CBSE
Three beakers labelled as A B and C each containing 25 mL of water were taken A small amount of NaOH anhydrous CuSO4 and NaCl were added to the beakers A B and C respectively It was observed that there was an increase in the temperature of the solutions contained in beakers A and B whereas in case of beaker C the temperature of the solution falls Which one of the following statements isarecorrect i In beakers A and B exothermic process has occurred ii In beakers A and B endothermic process has occurred iii In beaker C exothermic process has occurred iv In beaker C endothermic process has occurred
The branch of science which deals with nature and natural class 10 physics CBSE
What is the stopping potential when the metal with class 12 physics JEE_Main
The momentum of a photon is 2 times 10 16gm cmsec Its class 12 physics JEE_Main
Trending doubts
Difference between Prokaryotic cell and Eukaryotic class 11 biology CBSE
Difference Between Plant Cell and Animal Cell
Fill the blanks with the suitable prepositions 1 The class 9 english CBSE
Change the following sentences into negative and interrogative class 10 english CBSE
Give 10 examples for herbs , shrubs , climbers , creepers
What organs are located on the left side of your body class 11 biology CBSE
Write an application to the principal requesting five class 10 english CBSE
What is the type of food and mode of feeding of the class 11 biology CBSE
Name 10 Living and Non living things class 9 biology CBSE