Why does the setup of Davisson-Germer experiment need to be enclosed in a vacuum chamber? Discuss what result you expect when the chamber is not evacuated.

One of the key requirements of the Davisson-Germer experiment is the presence of a vacuum chamber. This is crucial because a vacuum environment ensures that there are no air molecules present which could come in contact with the electron beam. If the electrons were to collide with air molecules, the controlled scattering and diffraction of the electrons might be disrupted, leading to inaccurate results.

If the chamber is not evacuated, the presence of air molecules would cause interaction and scattering of the electrons in the beam, leading to inconsistencies in the experimental results. The electrons might lose their energy or be scattered in different directions due to their interaction with air molecules, causing the diffraction pattern to become less clear or even completely distorted.

When the chamber is not evacuated, the electrons' interference and diffraction patterns would be significantly affected. Instead of a clear diffraction pattern that is expected for the wave nature of the electrons, the experiment might yield a distorted or unclear interference pattern. In extreme cases, we might not be able to obtain any meaningful results due to a high level of scattering caused by the presence of air molecules in the chamber. In summary, evacuating the chamber is essential for the success of the Davisson-Germer experiment, as it removes any interfering particles that could disrupt the electron diffraction pattern. Failure to evacuate the chamber would lead to inaccurate results and a lower likelihood of observing the wave nature of electrons through diffraction.