|
Click the button below to play an audio file.
|
|
The rules for refraction for the two types of lenses (see Know the Law sections) have some details associated with them. Attention must be given to these details and to the details of the diagrams which are provided. The type of lens that is being shown is a critical detail. And in addition to that, the precise direction of any angled ray is of utmost importance. Make sure that the ray is passing through F (and not 2F) or that it is heading in line with F (and not 2F) if that is the direction it is suppose to travel. If necessary, place a straight edge upon the monitor in line with the ray to see if its extension passes through F or 2F.
|
|
The adoption of an effective strategy is often the key to success on a physics question. The following strategy should serve you well:
- Inspect Diagram A and determine the type of lens which is being shown.
- Identify the incident ray as being either a ray passing parallel to the principal axis or as a ray of light which is passing through the focal point (converging lens) or towards the focal point (diverging lens).
- Referring to the rules of refraction for the specific lens which is shown, determine if the diagram shows the specific ray which you have identified refracting in the proper manner. If it does, then the diagram can be listed as part of the answer. sections.)
- Repeat for the other diagrams.
|
|
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.
|
|
|
Diverging Lenses - Rules of Refraction
Light refracts at any boundary - including those that bound a lens material - according to Snell's law. For diverging lenses, some generalizations can be made to simplify ray construction. They are:
- An incident ray traveling parallel to the principal axis will refract and travel in a direction that is in line with the focal point on the original side of the lens.
- An incident ray traveling toward the focal point located on the opposite side of 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.
|