The experimental evidence that electrons behave with both particle and wave properties, depending on the experiment, is a corner stone of quantum mechanics. Up to the 20th century the particle nature of the electron was well established by J.J. Thompson through a series of experiments that followed the trajectories of electrons in a combination of electric and magnetic fields. With the development of quantum mechanics, the idea that electrons must behave like waves was postulated by DeBroglie. It was until Davisson and Germer's electron diffraction experiment early in the 20th century that the wave nature of an electron was directly observed.
In this lab you will conduct two experiments and also do a simulated x-ray diffraction measurement. In the first experiment you will perform an experiment similar to Davisson and Germer's and demonstrate that electrons interfere with themselves as if they were waves. In the second experiment you will then demonstrate the particle nature of an electron by measuring their trajectory in a magnetic field to give the e/m ratio. For the x-ray diffraction simulation you will identify the diffraction lines from a NaCl crystal and use this information to predict the diffraction lines from a graphite sample. You will also be asked to comment on the determination of the short wavelength limit of the x-ray spectrum from an x-ray tube and note its interpretation in terms of the particle nature of x-rays.
| School of Physics at Georgia Tech |