Temperature of a "Red Hot"Object

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Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Faughn, Jerry S., Serway, Raymond A. College Physics: Fifth Edition. Philadelphia: Saunders, 1999. "Wien's displacement law:
λmaxT = 0.2898 × 10-2 m.k"
555 °C
"Red Heat." Dictionary of Science and Technology. New York: Larousse, 1995. "As judged visually, a temperature between 500 °C and 1000 °C." 500–1000 °C
Hodyman, Charles D., Lange, Norbert A. Handbook of Chemistry and Physics. Cleveland, OH: Chemical Rubber Co., 1924.
Color Temperature
°C K
Incipient red heat 500-550 770-820
Dark red heat 650-750 920-1020
Bright red heat 850-950 1120-1220
Yellowish red heat 1050-1150 1320-1420
650–1150 °C
Process Associates of America. Metal Temperature by Color.
Color Approximate Temperature
°F °C K
Faint Red 930 500 770
Blood Red 1075 580 855
Dark Cherry 1175 635 910
Medium Cherry 1275 690 965
Cherry 1375 745 1020
Bright Cherry 1450 790 1060
500–790 °C

An object, at a certain temperature can emit radiation. This type of radiation is known as thermal radiation. The color of the radiation is dependent on the temperature and (according to Serway and Faughn) the properties of the object. As the temperature increases, the object begins to emit light.

The thermal radiations comes from accelerated charged particles near the surface of the object. The charged particles would emit radiation. This is the classical theory of thermal radiation.

A black body is an ideal system that absorbs all of the incident radiation on it. As the amount of energy it emits increases, so does the black body's temperature. As the temperature is increasing, the acme of the distribution move towards short wavelength. This obeys Wien's displacement law.

λmaxT = 0.2898 × 10-2mK

Where λmax is the wavelength at which the curve peaks and T is the temperature at which the object would emit radiation.

Stephanie Lum -- 2000


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