Franck-Hertz apparatus

The Franck-Hertz apparatus is a device used to demonstrate the quantized nature of energy in atoms. It consists of a tube containing gas, where electrons are accelerated and collide with gas atoms. When electrons collide with just the right amount of energy, they excite the atoms, causing them to absorb energy. This leads to a drop in current, which can be measured. The experiment shows that atoms have specific energy levels, and electrons can only gain energy in discrete amounts, illustrating key concepts in quantum mechanics. This was a pivotal experiment in understanding atomic structure.