• id: JME-10-N14
• title: Wien's Law and Color Temperature
• tags: wien, displacement, wavelength

Wien's law: $\lambda_{\max} T = b = 2.898 \times 10^{-3}$ m K. The wavelength at which a blackbody emits maximum radiation is inversely proportional to its absolute temperature. Applications: the Sun ($T \approx 5800$ K) has $\lambda_{\max} \approx 500$ nm (visible, yellowish). A hot iron rod ($T \approx 1000$ K) has $\lambda_{\max} \approx 3$ micrometers (infrared — it glows red because the tail of the distribution extends into visible red). Human body ($T \approx 310$ K): $\lambda_{\max} \approx 9.4$ micrometers (far infrared — detected by thermal cameras).