# Unraveling the Mysteries of Intensity vs Wavelength

• |mathematix|
In summary, the conversation discusses the relationship between wavelength and intensity of electromagnetic radiation, specifically in regards to the experiment and graph shown. The concept of quantification of energy and its role in the emission of ultraviolet light in quantum mechanics is also mentioned. The rarity of particles with a higher energy compared to the average is also brought up and confirmed that eV stands for electron volt.
|mathematix|
So people thought that as wavelength increases for electromagnetic radiation, intensity of radiation increases but this would mean that people would melt if exposed to any radiation higher than visible light. But then they did an experiment and they sketched the graph of the experiment which is the true graph of intensity vs wavelength.

I get everything up to this point but I would very much appreciate it if someone explains to my why intensity would decrease after the peak intensity at the visible light range? What does it have to do with quantification of energy? Also, what is the proper derivation of E=hf?
I really want to have a complete understanding of this because it is very important to understand Einsteins explanation of the photo electric effect and the the rest of quantum mechanics.

Thank you!

To get ultraviolet light in quantum mechanics, you need some minimal amount of energy - the energy of a photon. This rarely happens, so the total energy emitted as ultraviolet radiation is finite.
In classical thermodynamics, this minimal amount is not required - you would expect that everything, everywhere, would emit a lot of ultraviolet radiation.

mfb said:
To get ultraviolet light in quantum mechanics, you need some minimal amount of energy - the energy of a photon. This rarely happens, so the total energy emitted as ultraviolet radiation is finite.

Why does it rarely happen?

If the average energy per particle is something like 0.1 eV , particles with an energy of 3 eV and more are rare.
(if you don't know eV: does not matter, just compare 3 and 0.1)

mfb said:
If the average energy per particle is something like 0.1 eV , particles with an energy of 3 eV and more are rare.
(if you don't know eV: does not matter, just compare 3 and 0.1)

Ok, thank you!
eV is electron volt isn't it?

|mathematix| said:
Ok, thank you!
eV is electron volt isn't it?

yes.

## 1. What is intensity vs wavelength?

Intensity vs wavelength is a scientific concept that refers to the relationship between the intensity or brightness of light and its corresponding wavelength or color. It is often used to describe the energy or power of a light source at different wavelengths.

## 2. How is intensity vs wavelength measured?

Intensity vs wavelength is typically measured using a spectrophotometer or spectrometer, which can detect the intensity of light at different wavelengths. The data collected is then plotted on a graph to show the relationship between intensity and wavelength.

## 3. What factors affect intensity vs wavelength?

There are several factors that can affect the intensity vs wavelength relationship, including the type of light source, the material that the light is passing through, and the distance between the light source and the detector. Other factors such as temperature and pressure can also play a role.

## 4. How is intensity vs wavelength used in scientific research?

Intensity vs wavelength is a crucial concept in many scientific fields, including physics, chemistry, and biology. It is used to study the properties of light and its interactions with matter, as well as to analyze the composition of substances and identify unknown materials.

## 5. What are some real-world applications of intensity vs wavelength?

Intensity vs wavelength has many practical applications, such as in the development of new lighting technologies, the detection and analysis of pollutants in the environment, and the study of the chemical and physical properties of materials. It is also used in medical imaging techniques, such as MRI and PET scans, to visualize and diagnose diseases.

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