Emission of Infrared radiation

In summary: Welcome to PF. Yes, "infrared" is a range of frequencies, not a specific frequency. Energy can be determined by measuring the amount of energy emitted in a specific frequency. For example, if you want to know what electromagnetic energy a fish emits, you could measure its energy in microwaves.
  • #1
BBRadiation
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Question regarding the emission of infrared radiation, for personal knowledge.

Why do humans emit infrared radiation? Is it because it just so happens that the energy humans absorb (from sunlight)/ the energy humans produce just so happens to correlate to the frequency of infrared, as according to E = hf? Or am I wrong in my assumptions of where the source of the energy comes from?

Additionally, I read that many everyday objects, such as an ice cube or a textbook emit infrared. How can objects such as these, which have a much lower temperature than humans (which I assume correlate to lower energy) emit in the same frequency. Can this only be the case if infrared has a large spectrum, and thus can correlate to different amounts of energy?
 
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  • #2
Welcome to PF.
BBRadiation said:
Why do humans emit infrared radiation? Is it because it just so happens that the energy humans absorb (from sunlight)/ the energy humans produce just so happens to correlate to the frequency of infrared, as according to E = hf? Or am I wrong in my assumptions of where the source of the energy comes from?
All objects emit electromagnetic radiation in relation to their temperature via the mechanism of black body radiation: http://en.wikipedia.org/wiki/Blackbody

So the source of that energy is our internal body heat, which we generate using food as fuel.
Additionally, I read that many everyday objects, such as an ice cube or a textbook emit infrared. How can objects such as these, which have a much lower temperature than humans (which I assume correlate to lower energy) emit in the same frequency. Can this only be the case if infrared has a large spectrum, and thus can correlate to different amounts of energy?
Yes, "infrared" is a range of frequencies, not a specific frequency.
 
  • #3
Thanks a lot. Is the energy we generate from food the sole source of energy? Or does other factors play a role, such as friction from movement or absorption of energy from the sun?

If all these factors are prevalent, how does one determine the energy of an object? For example, if I wanted to know what electromagnetic energy a fish emits, how would I calculate its energy?
 

1. What is infrared radiation?

Infrared radiation (IR) is a type of electromagnetic radiation that is invisible to the human eye. It has longer wavelengths and lower frequencies than visible light, and is often described as heat radiation because it is responsible for the warmth we feel from objects.

2. How is infrared radiation emitted?

All objects with a temperature above absolute zero (-273.15°C) emit infrared radiation. This is because the atoms and molecules in the object are constantly vibrating and emitting energy in the form of electromagnetic waves, including infrared.

3. What are the sources of infrared radiation?

Infrared radiation is emitted by numerous sources, both natural and man-made. The sun is the primary source of infrared radiation, but other sources include fire, geothermal heat, and even the human body. In addition, many electronic devices, such as remote controls and thermal cameras, also emit infrared radiation.

4. What are the applications of infrared radiation?

Infrared radiation has many practical applications in various fields. Infrared cameras are used in thermal imaging to detect heat signatures, making them useful in law enforcement and search and rescue operations. Infrared heaters are also used for heating and drying, and in food processing to cook or preserve food. In addition, infrared radiation is used in spectroscopy to identify chemical compounds and in astronomy to study celestial objects.

5. How does infrared radiation affect the Earth's climate?

Infrared radiation plays a crucial role in Earth's climate as it is responsible for the greenhouse effect. The Earth's atmosphere traps some of the infrared radiation emitted by the Earth's surface, keeping the planet warm enough to sustain life. However, an increase in greenhouse gases, such as carbon dioxide, can trap more infrared radiation and lead to a rise in global temperatures, causing climate change.

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