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The diagram shows an incident ray approaching a lens. Upon striking the lens this ray will ____.
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Converging Lenses - Rules of Refraction
Light refracts at any boundary - including those that bound a lens material - according to Snell's law. For converging lenses, some generalizations can be made to simplify ray construction. They are:
- An incident ray traveling parallel to the principal axis will refract and pass through the focal point on the opposite side of the lens.
- An incident ray traveling through the focal point on the way to the lens will refract and travel parallel to the principal axis.
- An incident ray traveling through the exact center of the lens will refract upon entering the lens and upon leaving the lens and continue traveling in its original direction.
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Unlike mirrors in which light can only reflect off the mirrored side, a lens is transparent and can allow light to be transmitted through it from either side. Thus, a lens has two focal points. The two focal points on this diagram are distinguished from each other using a prime symbol: F and F '. Be cautious to distinguish between these points as you select your answer.
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Certain rays of light refract through a converging lens in a rather predictable manner. The behavior of these rays - known as principal rays - are of vital importance. You should quickly become familiar with the rules for how these rays refract. See Know the Law section.
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