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According to Wikipedia visible light lie between 405-790 THz https://en.wikipedia.org/wiki/Visible_spectrum

Can I just sum "maximum" spectrum of the light if by definition white light is sum of colors (frequencies)?

Like 405+790?

I just want to know what is frequency of bombarding by photons "white" noise rather specific "color"

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It seems from the way you have phrased your question that you think the frequency of the light corresponds to the number of photons per second. That's not the way it works. The number of photons per seconds would correspond to the brightness of the light for example you could have relatively few blue photons per second in the case of dim blue light or many blue photons per second for bright blue light of the same colour.

The frequencies you quote are (405 THz - 790 THz) are the frequencies of each individual photon of a certain colour. For example every photon of light from a red laser might have a frequency of 474 THz whether there are lots of them for bright light or few of them for dim light. For light from a blue laser all the photons might have a frequency of 620 THz etc.

So, I don't think there is really a good answer to your question. White light is made up mix of photons with different frequencies. The frequencies of photons, in the sense of how many photons arrive at some surface per second, would depend on the brightness of the light.

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  • $\begingroup$ OK. Thank you for your answer. Can I say that bright light source had frequency more than ultraviolet light (per second) because of cumulative frequency overlay? (exclude even all non visible spectrum from which is white light too) $\endgroup$ – Pierre May 21 at 13:03
  • $\begingroup$ It still sounds like you are trying to compare apples and oranges. Let's do a rough calculation. Say you had a 60 W incandescent bulb ~5% efficient so 3 W of light energy. Let's pick yellow light in the middle of the visible spectrum so f=5x10^14 Hz. The energy of one photon is given by E=hf = 6.6x10^-34 x 5x10^14 = 3.3x10^-19 J. Dividing 3 J/s by the energy per photon gives 9x10^18 photons per second. So this number is more than the frequency of a single UV photon but it all depended on what power of bulb we decided to start with. $\endgroup$ – M. Enns May 21 at 14:39
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As M Enns, said white light is a mixture of individual photons with different frequencies. There is no overall frequency or color for white light. The only reason we see white light is because our eyes have evolved to receive individual photons of different frequencies. We have different receptors which interact with different frequencies. As this video shows there is no white light involved. https://youtu.be/ZUlRH5ouBrY

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