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Description
An interactive, parabolic mirror, that shows how light from a fixed point is reflected in parallel rays. students can slide the position of the light bulb (to find the focus), and change the shape of the parabola (using a slider).
Bonus: Rather than having static lines to represent light rays, have a subtle animation (e.g. small arrows or beads slowly flowing along the ray, in the direction of the light).
Bonus 2: A few other types of shapes (e.g. semicircle), to show that slight rays are reflected differently.
Bonus 3: Swap the graphics to show how to heat an egg on a parabolic grill, using incoming light from the sun, or concentrate radio waves onto a detector in a radio telescope.