L6-21
Determine the focal point of a concave lens.
Parallel rays incident on a diverging plano-concave spherical lens appear to emanate from the focal point of the lens. Optionally, two plano-concave diverging lenses can be placed together to increase the divergence and decrease the focal length. A slit baffle with concave and convex lenses may be used to create a set of parallel rays, which can be varied in number, color, and in spacing.

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