Lecture

Radiative Power of Human Body and Blackbody Radiation

Graph Chat

Chat with Graph Search

Ask any question about EPFL courses, lectures, exercises, research, news, etc. or try the example questions below.

DISCLAIMER: The Graph Chatbot is not programmed to provide explicit or categorical answers to your questions. Rather, it transforms your questions into API requests that are distributed across the various IT services officially administered by EPFL. Its purpose is solely to collect and recommend relevant references to content that you can explore to help you answer your questions.

Description

This lecture covers the calculation of radiative power emitted by a human body behaving as a blackbody, the characteristic wavelength of emitted radiation, and the impact of ambient air radiation on the emitted power. It also discusses the power required to maintain human metabolism. Through exercises, students learn to apply Stefan-Boltzmann and Wien's laws to determine radiative power and understand the energy balance in human thermoregulation.

Official source

Related concepts (27)

Black-body radiation

Black-body radiation is the thermal electromagnetic radiation within, or surrounding, a body in thermodynamic equilibrium with its environment, emitted by a black body (an idealized opaque, non-reflective body). It has a specific, continuous spectrum of wavelengths, inversely related to intensity, that depend only on the body's temperature, which is assumed, for the sake of calculations and theory, to be uniform and constant.

Planck's law

In physics, Planck's law (also Planck radiation law) describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature T, when there is no net flow of matter or energy between the body and its environment. At the end of the 19th century, physicists were unable to explain why the observed spectrum of black-body radiation, which by then had been accurately measured, diverged significantly at higher frequencies from that predicted by existing theories.

Stefan–Boltzmann law

The Stefan–Boltzmann law, also known as Stefan's law, describes the intensity of the thermal radiation emitted by matter in terms of that matter's temperature. It is named for Josef Stefan, who empirically derived the relationship, and Ludwig Boltzmann who derived the law theoretically. For an ideal absorber/emitter or black body, the Stefan–Boltzmann law states that the total energy radiated per unit surface area per unit time (also known as the radiant exitance) is directly proportional to the fourth power of the black body's temperature, T: The constant of proportionality, , is called the Stefan–Boltzmann constant.

Wien's displacement law

Wien's displacement law states that the black-body radiation curve for different temperatures will peak at different wavelengths that are inversely proportional to the temperature. The shift of that peak is a direct consequence of the Planck radiation law, which describes the spectral brightness or intensity of black-body radiation as a function of wavelength at any given temperature. However, it had been discovered by Wilhelm Wien several years before Max Planck developed that more general equation, and describes the entire shift of the spectrum of black-body radiation toward shorter wavelengths as temperature increases.

Wien approximation

Wien's approximation (also sometimes called Wien's law or the Wien distribution law) is a law of physics used to describe the spectrum of thermal radiation (frequently called the blackbody function). This law was first derived by Wilhelm Wien in 1896. The equation does accurately describe the short wavelength (high frequency) spectrum of thermal emission from objects, but it fails to accurately fit the experimental data for long wavelengths (low frequency) emission.

Related lectures (41)

Science of climate change: radiation

Explores the impact of radiation on climate, covering the Earth's energy balance, biosphere, cryosphere, and carbon cycle.

Radiation Principles: Understanding Atmospheric Interactions

Introduces the principles of atmospheric radiation and its impact on climate change.

Blackbody Emission and Radiation Transport MOOC: The Radio Sky I: Science and Observations

Covers the transport equation for blackbody emission and radiation transport.

Emission of Thermal Radiation

Explores the emission of thermal radiation, covering mechanisms, electromagnetic radiation, temperature relationship, spatial distribution, and black-body radiation.

Thermal Radiation: Solar Collector MOOC: Thermodynamics I