optics.gif (6954 bytes)


LARGE SPHERICAL (Parabolic) MIRROR








EQUIPMENT

    redball.gif (326 bytes) Large Parabolic Mirror
   
redball.gif (326 bytes) Blue Carbon Filament Lamp
   
redball.gif (326 bytes) Ball on a String
    redball.gif (326 bytes) Reference Board with clamps




NARRATIVE
               The large parabolic mirror may be described as a spherical mirror, although it is a parabolic reflector from a WWI searchlight. Two of these mirrors are available.

            Place the 110 VAC blue carbon filament lamp at the center of curvature of the mirror. (The guide board which is clamped to the table is marked "C" for center of curvature and "F" for focal point.) Adjust the height of the bulb at this point so that the inverted real image is touching the object lamp "top to top".  Slide the lamp through the focal point to show the inversion of the image and its apparent point to show the inversion of the image and its apparent relocation behind the mirror.

            Put a wooden ball with a long string (a pendulum) near the focal point, and swing the ball.