19.4 Main Ideas & Assignment 12
At the start of this lesson you were asked the following essential questions:
- What is a thin lens?
- How are ray diagrams used to predict image characteristics for thin lenses?
- How is the thin lens equation used to predict image characteristics for thin lenses?
In this lesson you learned that a thin lens is a circular piece of transparent material with a spherically shaped convex or concave surface. A converging lens has a convex surface that refracts rays parallel to the principal axis toward a focal point, producing a real image (assuming the object is farther than 1 focal length away from the lens). A diverging lens has a concave surface, refracting rays that are parallel to the principal axis outwards so that they appear to have originated from a virtual focal point, producing a virtual image.
Similar to ray diagrams for curved mirrors, many rays produce the image but only a few are required to identify its characteristics. A ray diagram with three or more rays can be used to accurately predict the image characteristics formed by both types of lenses.
The lens equation
, which is identical to the curved mirror equation, can also be used to identify and predict image characteristics. Human vision is a good example of an optical system that can involve multiple lenses causing precise amounts of refraction to produce a clear image on the retina of the observer.
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Assignment 12 Word
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