Yesterday I was asked a question about how the light is added or whether the light was able to add up in reference to if two lights are placed, the result was double light.
Let us answer this question.
No, the lights do not add up in the strict sense of the word. Not by putting two lights together you get a light that gives “double”. To understand this we simply have to see the light as a wave and understand what a wave is like.
A wave has two parts, amplitude and frequency. The amplitude of a wave is the maximum amount that travels during the time, that is, the farthest it separates from an equilibrium position. The frequency is what it takes a wave to return to the same position, that is, what it takes to be at the same amplitude. It is the image, the amplitude would be 2 and the frequency 4.
The light has two parts by all known, the part as particle, the photon and the part as wave. As we know, light acts both ways and therefore, if we think of adding it, we must add both effects.
Adding two waves has its “that” since it is necessary to add both its amplitude and its frequency giving, for this, very interesting effects since it can from cancel the wave until simply nothing happens to be different lengths. That is, adding the light is something complicated. And this without taking into account that the light, in itself, vibrates in all directions. That is, a wave, as you have seen in the example vibrates in 2 directions. Well, the light vibrates in all.
Therefore, if we want to “add” the light in order to be able to increase its amplitude and it seems that, at the same frequency, of more “intensity” we have to make the waves overlap. For this they must go to the same frequency, have vibrated in the same direction and have to be emitted at the same time or, at least, not yet emitted at the same time, the point where we want to measure arrive at the same time.
This is very important because of a phenomenon called interference. When two lights are “in phase” ie they have the same frequency, the waves, when added, create zones where the sum of the waves gives no wave or gives an amplitude sum. That is, it gives dark or nothing or gives light. This phenomenon is called interference and depends on the distances that make the phase vary, is very easy to understand.
These are the reasons why the light does not add up, just as it happens to the sound, or like making twice noise, the result is not twice the noise, because it is a wave and you have to think how to treat it as such .
So, when you say whether the light adds up or you can not give a great explanation and know the answer only knowing how the light works and, of course, how a wave works because, in the end, the light is nothing more than An electromagnetic wave.