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### Significance of intensity

Posted: Sat Apr 21, 2018 3:19 pm
So I understand that intensity of light does not affect the Energy, frequency does. So what exactly is the importance of the intensity of light? Is it just the amount of photons? Can someone clarify please.

### Re: Significance of intensity  [ENDORSED]

Posted: Sat Apr 21, 2018 3:36 pm
When light acts as a particle/photon as in the photoelectric effect, the intensity does refer to the amount of photons. The significance is that there is a 1:1 ratio between photons and ejected electrons (with sufficient frequency). So, if we double the intensity of the light, we'll have twice as many electrons ejected. But, if the light is of insufficient frequency, increasing the intensity will have no effect.

### Re: Significance of intensity

Posted: Sat Apr 21, 2018 9:11 pm
Continuing off that note, when light acts as a wave, or for any wave, the intensity relates to the amplitude/height of the wave.

### Re: Significance of intensity

Posted: Sat Apr 21, 2018 9:48 pm
I also believe that the intensity is another word to describe brightness, so the higher the brightness, the greater the intensity.

### Re: Significance of intensity

Posted: Sun Apr 22, 2018 5:14 pm
Emma Leshan wrote:Continuing off that note, when light acts as a wave, or for any wave, the intensity relates to the amplitude/height of the wave.

Specifically, I think in one part of the textbook it referenced that in terms of the wave model intensity is proportional to the square of amplitude to the wave.
It also referenced that for the particle model, intensity was "proportional to the number of photons in an instant".

### Re: Significance of intensity

Posted: Sun Apr 22, 2018 5:17 pm
The intensity of light is the amount of photons. That is why making a light more intense will not result in an electron being removed from an atom. Each individual photon needs enough energy to remove and electron.

### Re: Significance of intensity

Posted: Sun Apr 22, 2018 9:55 pm
When the energy of the photon is equal or greater than the threshold energy, then an electron can be ejected. By increasing intensity, you are increasing photons, so if and only if we can meet the threshold energy can increasing intensity result in more electrons being ejected.

### Re: Significance of intensity

Posted: Sun Apr 22, 2018 10:30 pm
Intensity is the number of electrons and affects the height of the wave.