Thermionic, field and photo-emission
Three ways to free electrons from a metal: heating (Richardson–Dushman J = AT²e^(−φ/kT)), a strong electric field, and light. Compare work functions, currents and the saturation behaviour of a vacuum diode.
About this experiment
| Subject | Physics |
|---|---|
| Class | 12 |
| Chapter | 11. Dual Nature of Radiation and Matter |
| NCERT section | 11.2 |
| Level | NCERT level |
| Time | about 12 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: thermionic emission · field emission · photoelectric emission · work function · Richardson
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- Photoelectric effect: stopping potential and Einstein's equation
- Thomson's experiment: specific charge e/m of the electron
- Heisenberg uncertainty principle with single-slit electron diffraction
- X-rays: continuous spectrum, characteristic lines, Moseley and Bragg