 channel for physics please subscribe my channel hello everyone and welcome back to another episode of physics partner today I brought a video about Davison and Germer experiment the Davison Germer experiment was conducted by Clinton Davison and Lester Germer at Western Electric between 1923 and 1927 in which electrons is scattered by the surface of a nickel metal crystal displayed a diffraction pattern this experiment confirmed Lois D Broglie's hypothesis of wave particle duality which he proposed in 1924 and was a watershed movement in the development of quantum mechanics the Davison and Germer experiment on other hand was designed to study the surface of nickel rather than confirm the D Broglie hypothesis the apparatus you can see here is actually the experiment setup of Davison German experiment you can see here on that side that is a nickel target and you can see an accelerating anode from where the electron beam is supposed to come over there a strike on nickel target and diffracted electron beam will go on that side here you can find one movable detector and this all is placed in a vacuum chamber and there is one heated filament also there which is used to produce the beam of electron in this video we are going to study the procedure of this experiment and post experiment observation of Davison German let's try to understand how it works an electron gun was taken which comprised of a tungsten filament f coated with barium oxide and heated by the low voltage power supply electrons emitted from this electron gun were accelerated to a desired velocity by applying suitable potential difference from a high voltage power supply these emitted electrons were made to pass through a cylinder perforated with fine holes along its axis thus producing a fine collimated beam this beam produced from the cylinder is made to fall on the surface of a nickel crystal you can see here it's going to fall on a nickel crystal this lead to scattering of electrons in various direction the intensity of the beam of electron is measured by electron detector which is connected to a sensitive galvanometer to record the current basically and can be moved on a circular scale so you can see with the changes of the angle the reading on galvanometer is going to be changed it's showing current also the intensity of a scattered electron beam is measured for different value of angle of scattering so I can start from let's say 15 and it's going towards as you can see here the intensity of the scattered electron beam is measured for different values of angle of scattering usually will take theta for that theta will be the angle between the incident and the scattered electron beams so this is like the incident and this one is a scattered beam by moving the detector on a circular scale of different position you can use the movable detector to find out the different intensities of a scattered electron beam let's talk about the observation of Davison German experiment by varying accelerating potential difference there are some observation has been made a strong peak was noticed in the intensity of the scattered electron for an accelerating voltage of 54 you can see the 54 voltages here at the angle of 50 let's make it a 50 and you can see the change so you can very clearly see that the very strong peak was noticed at the intensity of a scattered electron for an accelerating voltage of 54 at the scattering angle theta which is 50 so you can notice this peak at this moment where the voltage was 54 and the angle is 50 this peak can be explained as the result of constructive interference of electron scattered from different layer of the regularly spaced atom of the crystal so how we calculate the wavelength the wavelength of the matter waves was calculated with the help of electron diffraction we can use the formula of energy which is half MV square and Planck constant we can take we can calculate with the help of electronic diffraction and the wavelength will you can see here will be 0.167 nanometer if you correlate this Davison-Germain experiment and de Broglie relation according to de Broglie wavelength lambda associated with electron is given by lambda is equal to H divided by P the same result of 0.167 thus Davison-Germain experiment confirms the wave nature of electrons and the de Broglie relation now generally there is a one question arose here why nickel crystal are used in diffraction experiment the basic thought behind the Davison and German experiment was that the waves reflected from the two different atomic layers of a nickel crystal will have a fixed phase difference after reflection these waves will interfere either constructively or destructively hence producing a diffraction pattern that's why the nickel source is used okay that's all about Davison and German experiment I hope it is very clear to you now and I hope you enjoyed the video so thank you very much for your listening take care of yourself see you in the next video goodbye