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Curated by: Physics Explained (87 videos)
In 1900, Max Planck proposed the radical idea that # energy is quantised, meaning it can only be transferred in discrete packets, or quanta, rather than in a continuous flow Five years later, Albert Einstein expanded on this idea, suggesting that # light consists of particles called photons, with each photon’s energy proportional to its frequency. To calculate the energy of a single photon, we use a conversion factor called Planck’s constant—named in honour of Max Planck—which gives us the famous equation E=hf. For any light source, the total energy emitted must then be an integer multiple of this fundamental unit of energy: E_total=nhf And the total energy can only ever change in multiples of this fundamental unit. Energy is quantised. However, because h is so small, this energy quantisation went unnoticed for thousands of years—yet it now lies at the heart of quantum mechanics