Photoelectric effect for dummies

Today, in what I take my third coffee between rest and rest of the studies, I want to tell you about the photoelectric effect since these days I have been talking about things of photons that are able to move things.

The photoelectric effect is not a new thing, but has been “with us” since the XIX century and is the recognition that light is a wave and a particle at the same time.

The fact is that it is recognized that light is a particle (and very small, by the way) because it is observed as it is able to hit the electrons that are in the atoms. This can only be done if a photon is something physical.

Regarding its wave quality, it is indicated because the photoelectric effect is able to pass energy to what strikes, something, the transfer of energy, that can only make the waves.

And how does this look?. Well, it’s very simple. Heinrich Hertz, German physicist, realized, in an experiment that if it put light in a jump of current, this one was able to arrive at longer distances. Especially with certain types of light (more than with others). This made him think that the light had something to do with the current, although it was not very clear. And it is that even the question that the light was wave and photon was not very clear, until the friend Planck arrived (as you can see, for a physicist is a knife, is good for everything) who proposed the idea of ​​quantification of matter that was taken advantage of by Einstein that, I manage to explain the reason of this thing.

And, as we know, atoms have electrons in different orbits depending on the energy they have. To more energy (actually, a part is kinetic energy) is its orbit farther from the nucleus, simply because, as I said, the kinetic energy of the electron gives it more speed. As an example, if you go in a circular circuit and run faster, each time you go more towards the outside or you will have to turn more the steering wheel (that would be like putting more “gravitational” force).

When a photon comes around the world, charged with an energy towards an atom, hopefully, it can give a hit to that electron. When it gives a good blow, it transmits its energy modifying the orbit in which this one is. Come on, it’s a way to give energy to an atom. If this electron is of a material that tends to drop electrons because they are in its valence (ie, the outermost) layer, it is normal for the electron to escape from the nucleus.

This, friends, is the photoelectric effect, where a photon “creates electricity“.

And then you will say, then all materials radiate electrons when it gives them the light ?. Well, no. It depends on the material itself, whether it can withstand the absorption of that energy because its electrons are not all in the “outer” layers or if it is capable of emitting that energy which it abuses, for example, in heat. And so you have a coherent explanation of why things are heated in the light of the Sun. Come on, it depends on light and material as it is made atomically.

Also, as you will know (or not), the orbits of the electrons are jumps (it is part of quantum physics, quanta, knowing this, by Planck), then the necessary energy has to be enough to make it jump orbit.

The photoelectric effect is very interesting and is now being used to create superconductors at room temperature (and here you can study the actual problems and how it works too) by irradiating (through a glass) the metallic material to facilitate the movement of the electrons. That is to say, it is putting a light almost parallel to the cable so that, by the photoelectric effect, it creates a layer of loose electrons by the material that is exactly the one that is used to transport the energy and as insulating layer of the passing electricity By this, achieving the movement of electrons without almost lost of energy.

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