 By early 20th century, scientists were finally beginning to get comfortable with the idea that light could behave like a wave as well as a particle. And that's around the same time when another young mind wondered, what if matter also had wave-like properties? Would it be possible that just as radiations of dual nature, matter also has both wave and particle-like properties? And the young scientist who thought of this absolutely revolutionary idea was none other than Louis De Broglie. De Broglie proposed that every moving particle has a wavelength and he called that wavelength a De Broglie wavelength. And the equation for this was given by lambda is equal to h by p, where h is the Planck's constant and p is the particle's momentum. Now though this was just a theoretical proposal, his prediction and the De Broglie equation was confirmed experimentally through Davison-Germain experiment. So let's take a quick peek at the Davison-Germain experiment that helped De Broglie win his Nobel Prize in Physics. So to explain briefly, two scientists named Clinton-Davison and Lester-Germain were experimenting with a beam of electrons and a nickel target. They were basically firing a beam of electrons at a nickel target and observing how the electrons were scattered. But unfortunately, not only did this experiment not work, their equipment was damaged and the nickel target got completely oxidized. So what they did was they tried to remove the oxide layer on the nickel by heating it and then decided to repeat the same experiment with the same sample. Of course now the nickel sample that they used was the heated one. And boom, to their surprise they found that the electrons in this case did not just scatter randomly. Instead, they formed a diffraction pattern just like the light waves did in the Young's double slit experiment that helped scientists prove the wave nature of light. I'm not sure how many of you remember this experiment where light was passed through two narrow slits and instead of getting two single spots, we actually got a wave. So while this proved the wave-like nature of light, something similar was obtained in this case where we bombarded electrons on the nickel target and obtained a similar diffraction pattern. Now this clearly demonstrated the wave-like behavior of electrons. And this was something that had never been observed before with a particle. Now this directly confirmed the De Broglie's prediction that particles like electrons can behave like waves. And the wavelength of the electrons calculated from this diffraction pattern matched the De Broglie wavelength given by the equation lambda is equal to H by P. Now you might wonder, we used the same nickel target in both the cases. How did we obtain a diffraction pattern in the second case? Well, turns out that they did not get a diffraction pattern the first time because a nickel target that was used was made up of many tiny crystals. Basically, it was a polycrystalline material and atom of the nickel sample was oriented in different directions. So when they fired the electron beam onto this nickel sample, the electrons got scattered in all possible directions because the atoms themselves were not arranged in a regular pattern. But when they heated the nickel sample to remove the oxide layer, the atoms on the surface now got enough energy to rearrange themselves and form a single crystal. Because the atoms were now arranged in a regular pattern, the scattered electrons formed a beautiful diffraction pattern. And this diffraction pattern proved the wavelet nature of particles. Now although matter has wavelet properties, we don't really observe it in our everyday life. You see, the things that we see around are so big and macroscopic and they have such large masses that they have a very large momentum because P is equal to MV and according to De Broglie equation, a large momentum would mean a short wavelength. These wavelengths are so short that the wave properties for large objects become almost completely insignificant. And that is why the De Broglie wavelength makes most relevance to subatomic particles like electrons that have very less mass. De Broglie wavelength was extremely significant and laid the cornerstone or foundation for the quantum mechanical model of atom. So let's learn more about the subatomic world in the subsequent videos.