Franck-Hertz Experiment
Experimental verification of the Bohr model and quantum energy states through inelastic electron collisions.
Project Overview
The Franck-Hertz experiment is a cornerstone of quantum mechanics, providing the first direct experimental proof of the Bohr model of the atom. In this project, I measured the quantized energy loss of electrons colliding with Mercury (Hg) and Neon (Ne) atoms.
By analyzing the current-voltage ($I-V$) characteristics, I observed distinct periodic drops in current, corresponding to the electrons transferring exactly enough kinetic energy to excite the atoms to their next energy state. This verified the discrete nature of atomic energy levels, governed by the relation $E = h\nu$.
Key Concepts Investigated
Quantum Quantization
Observed that energy transfer is not continuous but discrete. Electrons only lose energy when their kinetic energy measured experimentally ($K = eV$) matches the excitation energy of the atom.
Inelastic Collisions
Analyzed the mechanics of electron-atom scattering. Below the critical threshold, collisions are elastic; at the threshold, they become inelastic, causing the electron to lose almost all momentum.
Mean Free Path
Investigated how factors like temperature and gas pressure affect the mean free path of electrons, influencing the sharpness and spacing of the interference peaks.
Full Documentation
This report contains detailed data tables, error analysis, and theoretical derivations linking the observed voltage drops to the fundamental Planck constant.