Albert Einstein is probably the most famous physicist, up until this day. His legacy has transcended generations, and physics enthusiasts and common people alike. But although he is most famous for his theories on Relativity, namely Special and General Relativity, did you know that he received his Nobel Prize in Physics for his mathematical description of the photoelectric effect instead?
The photoelectric effect is the phenomenon where charged particles can be knocked off of and released from a certain material when light strikes its surface. This phenomenon was first discovered by German physicist Heinrich Rudolf Hertz back in 1887. However, nobody was able to explain how it works at that time. It was only 18 years later, when a mathematical description of this phenomenon was put forth by Albert Einstein in his corpuscular theory of light.
The photoelectric effect then became the foundation on where solar energy technology was built upon. Solar cells, which are the basic building blocks of solar panels, convert sunlight into electricity by utilizing this phenomenon.
How Solar Cells Work
First of all, solar cells are made from a very specific type of material that is called semiconductors. We all know about conductors and insulators; conductors easily permit the flow of electricity, while insulators prevent it. Semiconductors, on the other hand, have properties that are in between conductors and insulators. This makes them very suitable for converting light into electricity using the photoelectric effect.
Albert Einstein won the Nobel Prize in Physics for his description of the photoelectric effect because it has proved that light acts as particles, instead of waves, which was the belief of many physicists at that time. These particles that are called photons knock electrons out of their atoms by transferring their energy to them. When this happens, these electrons gain more energy and become free to move throughout the semiconductor material.
The next step toward's the solar cell's conversion process is to collect these free electrons in the solar cell's terminals so that it can be used as electricity. The solar cell accomplishes this by creating an internal voltage in the semiconductor material. This voltage guides the free electrons into the negative terminal of the solar cell, which will then be ready to be used as an electric current.
Is Light a Particle or a Wave?
Oddly enough, Einstein was not the first person to propose the corpuscular theory of light, which says that light is a particle. This was first done by Isaac Newton way back in 1672. By assuming that light is a particle, he was able to explain the geometric nature of light. Isaac Newton was then able to derive a whole new field of physics called optics , which he published on a paper entitled: "Opticks: or, A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light".
Almost 200 years later, however, a physicist named James Clerk Maxwell his electromagnetic theory which described in detail how light travels as electromagnetic waves. Newton's corpuscular theory of light was discarded as this new theory was very successful and was easily adopted by the scientific community.
At that time, it seemed that the debate of whether light is a particle or a wave has been decided once and for all. But as we have already mentioned, Albert Einstein came and proved that light is a particle through the photoelectric effect, which won him the Nobel Prize in Physics.
So, which is it really? The whole scientific community says that light is a wave, while two of the greatest physicists of all time, Newton and Einstein, says that it is a particle. Today, our understanding of quantum mechanics tells us that both matter and light has a wave-particle duality, which means that they can act as both particles and waves.
Einstein's Genius
Through Einstein's genius, we got the groundwork of solar energy, which was the photoelectric effect. And this happened because he had the courage to defy what everyone thought at that time and the determination to pursue the inner workings of the universe.
Let us then use this story as an inspiration: for us to also have the courage to defy our world's dependence on coal and other dirty fossil fuels and the determination to make the world a better place!
Engr. Jet Andal has 6 years of experience in the design and installation of residential, commercial and utility-scale solar PV systems. Together, and with the use of solar energy, let us help make the world a better place. You can click here to read all of our other blogs. For aspiring solar PV engineers, you can also check out his Solar PV Engineering Ebook on Amazon on this link.