Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an...
-
Upload
easter-garrett -
Category
Documents
-
view
219 -
download
0
Transcript of Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an...
![Page 1: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/1.jpg)
Thermal radiationAny object that is hot gives off light known as Thermal Radiation .
The hotter an object is, the more light it emits. As the temperature of the object increase, it
emits most of its light at higher and higher energies.
![Page 2: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/2.jpg)
The Electromagnetic Spectrum
10100
100010000
1000001000000
Wavelength
(nm)
infrared
visible
UV
![Page 3: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/3.jpg)
Black body
A black body is an object that absorbs all light that falls on it. Because no light is reflected or transmitted, the object appears black when it is cold.
A black body emits radiation at a given temperature and wavelength exactly as well as it absorbs the same radiation.
![Page 4: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/4.jpg)
Black body radiation spectrum
Wave length (nm)
![Page 5: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/5.jpg)
Solar radiation – Visible
6000 K
![Page 6: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/6.jpg)
6,000 K 300 K
Radiation from the Earth’s surface –Infrared
Note : To convert to nm multiply by 1000
![Page 7: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/7.jpg)
An image of a human hand taken in the infrared displayed in false color where white and yellow correspond to hot regions, blue and green to cool regions.
IR images
![Page 8: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/8.jpg)
IR Images
Some materials are transparent to infrared light, while opaque to visible light (note the plastic bag). Other materials are transparent to visible light, while opaque or reflective to the infrared (note the man's glasses)
![Page 9: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/9.jpg)
Boy holding cold ball
Boy holding hot ball
The temperature difference between a ball that is cold and one that has been heated. But also note the various warm areas on the boy's face.
IR images
![Page 10: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/10.jpg)
Shown above is an Infrared Map of the Earth. Red areas represent regions of high heat retention in the atmosphere.
IR images
![Page 11: Thermal radiation Any object that is hot gives off light known as Thermal Radiation. The hotter an object is, the more light it emits. As the temperature.](https://reader031.fdocuments.net/reader031/viewer/2022032200/56649cef5503460f949bd42a/html5/thumbnails/11.jpg)
The image shows a cat in the infrared. The orange areas are the warmest and the white-blue areas are the coldest.
IR images