# Intensity of Light- What factors contribute?

1. May 5, 2007

### AznBoi

Intensity of Light-- What factors contribute?

What factors affect the intensity of light? What is intensity? Are the relationships or equations that link the intensity of light to other variables? I'm asking this because I'm not quite understanding intensity vs. frequency. I'm studying the photoelectric effect and how no photoelectrons are emitted if the light has a frequency lower than the threshold of frequency regardless of how intense the incident radiation was.

2. May 5, 2007

### AznBoi

Okay, so I've read that increasing the intensity of the incident energy of light gives way to more photons and results in the ejection of more photoelectrons. So the intensity is basically energy? Photons are quantums if EM energy right? So basically the higher intensity a light source has, the more photons it emits and theirfore it results in more photoelectrons being ejected from a metal surface?

3. May 5, 2007

### AznBoi

Can someone explain why $$KE_{max}=E-\phi$$ given that E=hf and is fixed for all of the photons absorbed by the electrons. I know that the the minimum energy needed to liberate an electron from its atom is $$\phi$$ but I still don't get why the max KE is equal to E-Phi. Is it because it takes the electron Phi amount of energy to liberate itself and therefore the left over of the absorbed energy E minus Phi would give the energy left after liberation and this energy would equal the KE?

Last edited: May 5, 2007
4. May 5, 2007

### AznBoi

I know that a photon is a quantum of electromagnetic energy and that a quatm are individual bundles.. But can I also define a photon as a "particle of light/electromagnetic radiation and rays?" Are photons considered particles? Do they have a mass? Are they basically considered like gases or are they just bundles of energy?

5. Jul 29, 2010

### ttayang

Re: Intensity of Light-- What factors contribute?

can any one tell me the relationship between the intensity of light and the HSL value? HSL stands for hue, saturation, and lightness