Refraction and Lenses - Mission RL8 Detailed Help

The following diagrams are ray diagrams, showing how to locate the image (in GREEN) of an 'arrow object' (in RED). Which of these diagrams are correctly drawn? List all that apply ... .


Drawing Ray Diagrams:
Ray diagrams involve the construction of two or more rays from a location on the object in order to determine the location of the image. By drawing two or more incident rays and their corresponding refracted rays, the image location can be identified as the intersection point of the refracted rays. So a point on the extremity of the object is selected (the arrowhead in these diagrams). Then two of the three rules of refraction are used to draw two sets of incident and refracted rays (see Know the Law section). The location where the refracted rays intersect is the image location of the top of the arrowhead. The remainder of the image extends from the principal axis to the image of the arrowhead.

You are to identify the diagrams that are correctly drawn. The Know the Law section describes the method used to draw ray diagrams. Check each diagram carefully, making sure that the ...
  • principal rays were drawn starting from the arrowhead of the object
  • principal rays were drawn correctly (see Know the Law)
  • image was located where the principal rays intersected
If the diagram fails at any of the above three criteria, then the diagram is not correct.

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.