Coffee break time!

Coffee break time!

Take a picture of your coffee cup under a “point-source” of light (the sun, the light spot in your room, the torch of a mobile…). Now you can try to give reasons why the light rays form such a pattern on the coffee. The application below gives you the opportunity to create your own geometric model of the occurring physical phenomenon. By selecting the tools in the upper bar, you can build a geometric construction that models the behaviour of the light and returns almost the same pattern.

Once a geometric object (point, line, …) is placed on the plane, you can move it by dragging it with the mouse.

If you need some help you can move toward the application you find below this one (there you will get two hints about how to start building your model). If you want to go straight to one possible solution, click on the link at the bottom of the page.

Further explorations

  1. How does the curve change, if the light source moves exactly above the border of you cup? (Try this with your cup of coffee, then model the phenomenon with the app).
  2. What is the name of the curves formed on the coffee in the two cases?

Link to the Solution.

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