Understanding Thermal Radiation
The Efficient Engineer・2 minutes read
Objects emit thermal radiation due to their temperature, with electromagnetic waves traveling at the speed of light between objects. Engineers study these waves to understand heat transfer, with factors like wavelength and emissivity playing crucial roles in determining how much radiation is absorbed, reflected, or transmitted by an object.
Insights
- Engineers studying thermal radiation focus on the characteristics of electromagnetic waves, which travel in straight lines and can pass through a vacuum, with wavelength determining the type of wave.
- The emissive power of a body, measured in Watts per square meter, is crucial in understanding thermal radiation, with real bodies having emissivity values that define their radiation compared to a black body, impacting heat transfer between surfaces.
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Recent questions
What is thermal radiation?
Thermal radiation is the electromagnetic waves emitted by objects with a temperature above absolute zero, traveling at the speed of light.
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Summary
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Understanding Thermal Radiation in Heat Transfer
- Objects with a temperature above absolute zero emit electromagnetic waves that travel at the speed of light, producing thermal radiation.
- Thermal radiation, along with conduction and convection, is a method of heat transfer between objects.
- Engineers studying thermal radiation often begin by examining the characteristics of electromagnetic waves.
- Electromagnetic waves travel in straight lines from the emitter and can pass through a vacuum, a unique property of thermal radiation.
- The wavelength of an electromagnetic wave determines its type, with radio waves having long wavelengths and gamma rays having short wavelengths.
- The emissive power of a body, measured in Watts per square meter, is the total energy radiated per unit area each second.
- A black body, an ideal emitter, emits the maximum possible thermal radiation at a given temperature, calculated using the Stefan-Boltzmann law.
- Real bodies have emissivity values that define how much they emit compared to a black body, with emissivity varying with temperature and wavelength.
- Surface emissivity, absorptivity, reflectivity, and transmissivity play crucial roles in determining how much radiation is absorbed, reflected, or transmitted by an object.
- Heat transfer between surfaces due to radiation can be calculated using view factors, which describe the fraction of energy radiated from one surface that reaches another.
