Franck-Hertz experiment: quantised atomic energy levels
Accelerate electrons through mercury vapour; the current dips every 4.9 V as atoms are excited and emit 253.7 nm UV.
About this experiment
| Subject | Physics |
|---|---|
| Class | 12 |
| Chapter | 12. Atoms |
| NCERT section | 12.4 |
| Level | Advanced (JEE / Olympiad) |
| Time | about 14 minutes |
| Access | Included in a PractiSci plan |
What you do in the lab
Change the controls and watch the physics behave in real time in 3D. Live readouts and graphs show the numbers behind it, and the Learn tab has the theory, procedure, observations and viva questions. Works on a phone or a laptop, in English and Hindi.
Topics: Franck Hertz · energy levels · excitation · mercury