Quantum and Nuclear | Light, Sound and Waves

So what's new about chunks of energy?

Teaching Guidance for 14-16 Supporting Physics Teaching

Continuous streams and discrete chunks of energy

In introducing the idea that light shifts energy in discrete chunks, it is important to emphasise to students the key differences from a purely wave-based model:

In a wave model of light, energy is shifted in a continuous stream along the heating as radiation pathway. Imagine a continuous flow of the orange energy liquid introduced in the physics narrative Shifting energy between stores, gradually filling up an energy store as it is absorbed. With the photon model, the image is one of a stream of orange energy liquid droplets filling an energy store chunk by chunk. Furthermore, different kinds of light (infrared, visible, ultraviolet) have energy chunks, or photons, of different value. For example, ultraviolet photons can be thought of as larger droplets than infrared photons. In other words, ultraviolet light shifts energy in bigger chunks.

The same droplet-like model applies to emptying stores – no longer a steady outward flow of liquid, but a drip-by-drip emptying.

Teacher Tip: Now we're emptying and filling stores not by pouring orange liquid but spoonful by spoonful.

is exhibited by Photoelectric Effect
can be explained by the Bohr Model
can be described by the relation E=hf
2023 IOP Awards

Teachers of Physics Awards

Recognising and celebrating outstanding contributions to the field of physics education.

Learn more