Stefan-Boltzmann Law
Thermal radiation power P = εσAT⁴. σ ≈ 5.67×10⁻⁸ W/(m²·K⁴). Emissivity ε: 0–1. Blackbody ε=1. Net radiation between surfaces accounts for temperature difference.
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Sun: T ~ 5778 K, radiates ~3.8×10²⁶ W. Earth: absorbs and re-radiates to balance. Emissivity: polished metal ~0.05, black ~0.95. T⁴: small T change = large power change.
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Why: All bodies emit thermal radiation. Stefan-Boltzmann gives total power. Essential for heat transfer, climate, and stellar luminosity.
How: P = εσAT⁴. Emissivity ε depends on surface. Net radiation between two surfaces: P_net = σA(T₁⁴−T₂⁴) for blackbodies.
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☀️ Sun's Luminosity
Calculate the Sun's total radiated power. Temperature: 5778 K, Radius: 6.963×10⁸ m, Emissivity: 1.0
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👤 Human Body Radiation
Calculate thermal radiation from human body. Temperature: 37°C, Surface Area: 1.8 m², Emissivity: 0.98
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💡 Incandescent Light Bulb
Calculate radiation from incandescent bulb filament. Temperature: 2800 K, Surface Area: 0.0001 m², Emissivity: 0.35
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🌋 Lava Flow Radiation
Calculate radiation from lava flow. Temperature: 1200°C, Surface Area: 100 m², Emissivity: 0.95
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🏭 Industrial Furnace
Calculate radiation from industrial furnace. Temperature: 1500 K, Surface Area: 50 m², Emissivity: 0.85
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Input Parameters
Emissivity ranges from 0 (perfect reflector) to 1 (black body). Select a material to auto-fill.
Temperature of the surrounding environment for net radiation calculation.
For educational and informational purposes only. Verify with a qualified professional.
🔬 Physics Facts
P = εσAT⁴; σ = 5.67×10⁻⁸ W/(m²·K⁴)
— Stefan-Boltzmann
Blackbody: ε = 1; gray body: ε < 1
— Radiative transfer
T⁴ dependence: radiation grows rapidly with T
— Thermodynamics
Sun luminosity ~3.8×10²⁶ W
— Astrophysics
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