Absorptivity Of Small Body Using Absorbed Radiation And Temperature Calculator

Absorptivity Formula:

\[ \alpha = \frac{G_{abs}}{\sigma \times T^4} \]

Absorptivity (α):

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1. What is Absorptivity?

Absorptivity (α) is the fraction of incident radiation flux absorbed by a body. It is a dimensionless quantity that ranges from 0 (no absorption) to 1 (complete absorption), representing how effectively a surface absorbs thermal radiation.

2. How Does the Calculator Work?

The calculator uses the absorptivity formula:

\[ \alpha = \frac{G_{abs}}{\sigma \times T^4} \]

Where:

\( \alpha \) — Absorptivity (dimensionless)
\( G_{abs} \) — Absorbed radiation (W/m²)
\( \sigma \) — Stefan-Boltzmann constant (5.670367 × 10⁻⁸ W/m²K⁴)
\( T \) — Temperature (K)

Explanation: This formula calculates the fraction of radiation absorbed by a body based on the absorbed radiation energy and the body's temperature using the Stefan-Boltzmann law.

3. Importance of Absorptivity Calculation

Details: Absorptivity is crucial in heat transfer analysis, thermal engineering, and materials science. It helps determine how materials respond to thermal radiation, which is essential for designing thermal systems, insulation materials, and energy-efficient buildings.

4. Using the Calculator

Tips: Enter absorbed radiation in W/m² and temperature in Kelvin. Both values must be positive numbers. The calculator will compute the absorptivity coefficient.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of possible absorptivity values?
A: Absorptivity ranges from 0 to 1, where 0 means no radiation is absorbed (perfect reflector) and 1 means all incident radiation is absorbed (perfect black body).

Q2: How does absorptivity relate to emissivity?
A: For thermal equilibrium, according to Kirchhoff's law of thermal radiation, the absorptivity of a surface equals its emissivity at the same wavelength and temperature.

Q3: Can absorptivity be greater than 1?
A: No, absorptivity is a dimensionless fraction and cannot exceed 1. Values greater than 1 would violate energy conservation principles.

Q4: Does absorptivity depend on wavelength?
A: Yes, absorptivity is generally wavelength-dependent. The calculated value represents an average or effective absorptivity for the thermal radiation spectrum.

Q5: What factors affect a material's absorptivity?
A: Surface finish, material composition, temperature, wavelength of radiation, and surface coatings all influence a material's absorptivity characteristics.