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Glossary of Terms > F


A small camera used to video close up work. Can be used in the classroom through projectors or televisions to show the class documents or demonstrations. Click here for the Flexcam equipment page.

Focal point (focus)

The point at which converging rays meet and at which a clearly defined image can be obtained.


An influence on a body or system, producing or tending to produce a change in movement or in shape or other effects. Generally described as a push or pull.


The measurement of the number of occurrences of a repeated event per unit of time. The rate of change of phase in a waveform.

Fresnel (lens)

A glass lens comprising stepped concentric rings with a short focal length. Used in theatre spotlights and lighthouses.


Surface resistance to relative motion. The force which slows down moving objects.