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Define Emissivity of some materials at 300 K.

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.27P: Determine the rate of radiant heat emission in watts per square meter from a blackbody at (a) 15C,...

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Question

Define Emissivity of some materials at 300 K.

Expert Solution

Step 1

Thermal emissivity(ɛ) coefficient gives the heat or radiation absorbing and emission capacity of a material. For a black body the value of thermal emissivity is 1,hence it mean it absorbs all the incident radiation on it and emits them.

$\to ε = \frac{Radiant energy of an object at a given temperature}{Radiant energy of a blackbody at the same temperature}$

Thermal emissivity coefficient of a body depends on its temperature, material, nature of surface. $(0 < ε \leq 1)$

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