PURPOSE: To show how air currents cause the "twinkling" of a star.

DESCRIPTION: A laser beam is directed on a distant wall or screen. When the heater is positioned below the laser beam, hot air convection currents and density changes cause the beam to move continuously, or "twinkle."

The photograph at the right shows the "star" on a closer screen for illustration.

SUGGESTIONS:

REFERENCES: (PIRA unknown.) See also demonstration E2-48: NON-TWINKLING PLANET

See also the discussion of this demonstration on TecHKnow Wiki, a new free technician encyclopedia that anyone can change.

EQUIPMENT: Laser cart, hot plate with mount.

SETUP TIME: 5 min.