Description
Most school science textbooks present a classical interpretation of energy. While this provides a good approximation for describing macroscopic phenomena, it does not accurately depict the Einstein’s mass-energy (E=mc^2), nor Planck’s quantisation of energy (E=hf) relationships. For instance, it overlooks the subtle change in mass between reactants and products in a chemical reaction. Therefore, we developed a learning sequence for middle-school students using intuitive activities, framing c2 and h as massive and tiny conversion factors respectively.
First, students perform physical tasks to learn that work done (F×d) is directly related to the energy expenditure (E=mc^2, E=hf). Next, they explore the historical development of ideas about power and energy through a bucket-lifting task. They lift weighted buckets connected to a rope over a bar to simulate work done by pit ponies in a 17th-century coal mine. Students repeat this task using a setup powered by a solar panel instead of their muscles. They observe that the same mechanical work can be performed more efficiently using electrical energy generated by photons. Additionally, a toy solar panel activity illustrates how photon energy transfer takes place in solar cells through the photoelectric effect.
Finally, students investigate a toy version of a landmark experiment conducted at the Max Planck Institute that measured the tiny mass difference between two quantum states of an atom. The measured mass difference corresponded precisely to the energy of the transition photon, providing a direct experimental link between E=hf and E=mc^2 in which the mass change of an atom was measured after absorption and emission of a single photon (Schüssler et al., 2020). The toy model makes this beautiful experiment accessible using low-cost classroom materials.
Reference
Schüssler, R. X. et al. (2020). Detection of metastable electronic states by Penning trap mass spectrometry. Nature, 581(7806), 42–46. https://doi.org/10.1038/s41586-020-2221-0
| I am the presenting author | No |
|---|---|
| If you are not the presenting author, please give the presenting author's name: | Anastasia Lonshakova |