So after yesterday’s workshop on MI-U (Modeling Instruction, University level), I’m brainstorming possible “models” at the heart of a typical calc-based Physics II course, which I just happen to be teaching this fall. Here’s what comes to mind for models and their component sub-models…
In optics:
- ray model of light, which includes (as component models or sub-models):
- model of the human eye and perception of “images”
- Snell’s Law model of refraction
- law (model) of reflection
- wave model of light, which includes (as component models or sub-models):
- model of traveling waves
- model of standing waves
- model of polarization
In electricity & magnetism:
- Coulomb model of electric forces, which includes (as component models or sub-models):
- atom/electron/conductor/insulator model of charge buildup & transfer
- Coulomb’s model of electric forces
- electric field model (is Gauss’ Law a separate “model”, or just a tool accompanying the electric field model?)
- magnetic force model(s)
- magnetic field model
- Faraday model of electromagnetic induction
In circuits:
- DC current model of electric circuits, which includes (as component models or sub-models):
- “charge escalator” battery model
- Ohm’s Law model of current flow through materials
- Watt’s Law model of power dissipation
- series & parallel circuits “models” (??)
- AC current model of electric circuits, which includes (in addition to the DC model’s components):
- capacitor model
- inductor model
Am I making this too complicated?
I think it would be cool to have the meta-conversation about how fields are a model. Do they exist? Do they just help with calculations? I certainly say yes and no to those questions but I really wonder if the reality of fields is necessary for this level of material.
What is necessary to reify fields? For me, the propagation at c and concomitant lag when the particle accelerates are definitive. Are changing fields evidence, or can we usefully think of induction effects in terms of sources?
Oh, and Ian, I like your list. ASU has a Models of Light unit that includes particle/ray, wave, and photon models. I like to think of Models as including state variables and relations between them. Often, there are external things that drive changes over time. It seems that one can get as complex as one wants in making Models.
I’m really looking forward to challenging Ss to answer the question “What is real? Is energy ‘real’? Are fields? Etc…”