We had a fire drill, and I grabbed the large converging mirror. I don't want to stop with the ray model of light.
Today, though, felt a little repetitive. Oh, look, principal rays that are parallel to the axis. Oh, look, real, inverted, smaller than the object images that are located between f and 2f. We've seen this before. The analogy between mirrors and lenses are strong.
But the applications of lenses are more interesting. Every time I talk about lenses, I end up talking about how eyeglasses work. They're interesting, and I can explain people's prescriptions.
I talked a lot today. Tomorrow, everyone will talk. We'll need to think through the implications of the ray model.