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Physics, Astronomy & Cosmology / Re: What is the difference between emission and reflection?
« on: 29/07/2016 14:55:36 »
Hi Hamdani,
thank you. I am still not completely clear.
Every body having a nonzero temperature T emits radiation spread over several wavelengths (blackbody curve). The higher T the more the wavelength distributions shifts to lower wavelength. I get that, but I am still not clear why most thermometers measure the temperature of a body based on the radiation that the body emits in a narrow range in the infrared spectrum. For example, my Kintrex digital infrared thermometer with laser indicator is set to emissivity= 0.95 (almost a black body) and detection in the wavelength range 8-14 um. why that specific range? I know the human body radiation curve peaks at 10 micron. But most hot objects are hotter than the human body...What if two body had the same energy radiant energy concentration in that range but very different concentration outside that spectral range? Could we interpolate the rest of the blackbody curve and prove that they have the same T or not necessarily?
Is the thermometer giving us a skewed result? I have used this thermometer to measure very hot things (stoves, etc.) and I wonder if my results were wrong...
thank you. I am still not completely clear.
Every body having a nonzero temperature T emits radiation spread over several wavelengths (blackbody curve). The higher T the more the wavelength distributions shifts to lower wavelength. I get that, but I am still not clear why most thermometers measure the temperature of a body based on the radiation that the body emits in a narrow range in the infrared spectrum. For example, my Kintrex digital infrared thermometer with laser indicator is set to emissivity= 0.95 (almost a black body) and detection in the wavelength range 8-14 um. why that specific range? I know the human body radiation curve peaks at 10 micron. But most hot objects are hotter than the human body...What if two body had the same energy radiant energy concentration in that range but very different concentration outside that spectral range? Could we interpolate the rest of the blackbody curve and prove that they have the same T or not necessarily?
Is the thermometer giving us a skewed result? I have used this thermometer to measure very hot things (stoves, etc.) and I wonder if my results were wrong...