Emissivity Calculator

Surface Temperature (K):
Surrounding Temperature (K):
Wavelength (μm):
Calculate Emissivity:

Introduction

Calculating emissivity is crucial in various fields such as engineering, physics, and thermodynamics. Emissivity refers to the efficiency of a surface to emit thermal radiation compared to an ideal emitter, typically a blackbody. This article presents a simple and efficient calculator to determine emissivity.

How to Use

To utilize the emissivity calculator, follow these steps:

1. Enter the temperature of the surface.
2. Input the temperature of the surrounding environment.
3. Fill in the wavelength of interest (in micrometers).
4. Click on the “Calculate” button to obtain the emissivity value.

Formula

The formula used to calculate emissivity is given by:

\varepsilon = \frac{{\lambda_1}}{{\lambda_2}} \times \left( \frac{{e^{\frac{{hc}}{{k \cdot \lambda \cdot T}}}} – 1 \right)^{-1}

Where:

• ε is the emissivity.
• λ1​ is the upper limit of wavelength (in micrometers).
• λ2​ is the lower limit of wavelength (in micrometers).
• h is Planck’s constant (6.62607015×10−346.62607015×10−34 m² kg / s).
• c is the speed of light (2.998×1082.998×108 m/s).
• k is the Boltzmann constant (1.380649×10−231.380649×10−23 J/K).
• T is the temperature of the surface (in Kelvin).

Example Solve

Let’s assume:

• T=500 K (surface temperature).
• Ts​=300 K (surrounding temperature).
• λ=10 μm (wavelength).

Using the formula, we get:

\varepsilon = \frac{{10}}{{0.1}} \times \left( \frac{{e^{\frac{{6.62607015 \times 10^{-34} \times 2.998 \times 10^8}}{{1.380649 \times 10^{-23} \times 10^{-5} \times 500}}}} – 1 \right)^{-1}

After computation, the emissivity value is obtained.

FAQ’s

Q: What is emissivity?

A: Emissivity refers to the efficiency of a surface to emit thermal radiation compared to an ideal emitter, typically a blackbody.

Q: How does temperature affect emissivity?

A: Emissivity generally increases with temperature, as hotter surfaces emit more radiation.

Q: What is the importance of emissivity in engineering?

A: Emissivity is crucial in various engineering applications, including heat transfer analysis, thermal imaging, and materials science.

Conclusion

The emissivity calculator provides a convenient tool for accurately determining the emissivity of a surface, aiding in various scientific and engineering endeavors.