Temperature is closely linked to how objects emit electromagnetic radiation, the energy form that includes light, heat, and radio waves.
- All objects with a temperature above absolute zero (the coldest possible temperature) emit this type of energy.
- The key thing to understand is that the temperature of an object influences the wavelength of the radiation it emits the most.
- Hot objects: Emit more electromagnetic radiation at shorter wavelengths. Imagine a hot fire burning bright with blue hues. Similarly, hot objects emit a higher proportion of their energy at shorter wavelengths, which often appear bluish.
- Cold objects: Emit more electromagnetic radiation at longer wavelengths. Think of a dimmer fire glowing red. Colder objects emit more radiation at longer wavelengths, which tend to be perceived as redder.
- The relationship between temperature and the peak wavelength of an object’s radiation is described by Wien’s displacement law. This law states that the product of an object’s temperature and the peak wavelength of the radiation it emits is a constant.