So what's new about chunks of energy?
Teaching Guidance
for 14-16
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
.
