PURPOSE: Shows how rays are focused by a standard reflecting telescope.

DESCRIPTION: Parallel rays incoming from a star at infinity (red strings) are focused by the large mirror to a focus near the aperture of the telescope. The reflected rays (white strings) are intercepted before their focus by a small mirror, and deflected upwards toward the eyepiece of the telescope. The eyepiece is positioned at its focal distance past the focal plane of the objective (mirror).

SUGGESTIONS:

REFERENCES: (PIRA unknown)

EQUIPMENT: String model on tripod, as photographed.

SETUP TIME: 5 min.