Sun / SchoolA geometry lesson
with lunch at its center

A pot
at the
focus.

Parallel sunlight. One curved reflector. A very small place where the rays meet.

Focal pointParabolic reflector

Why a parabola?

For rays parallel to its axis, a parabolic mirror reflects light to a shared focal point. Tilt the mirror and that alignment breaks.

The geometry

y = x² / 4f

In this familiar equation, f is the focal length: the distance from the vertex to the focus.

A classroom model

This idealized diagram shows reflected ray directions. It does not predict cooking temperature. Real reflectors, sunlight and heat losses make a messier picture.