How to Draw Ray Diagrams for Concave Lens

March 06, 2022 Post a Comment

Diverging Lenses - Ray Diagrams

Before in Lesson 5, we learned how light is refracted by double concave lens in a manner that a virtual image is formed. Nosotros also learned nearly three simple rules of refraction for double concave lenses:

Any incident ray traveling parallel to the master axis of a diverging lens will refract through the lens and travel in line with the focal betoken (i.e., in a direction such that its extension will pass through the focal point).
Any incident ray traveling towards the focal point on the way to the lens will refract through the lens and travel parallel to the master centrality.
An incident ray that passes through the center of the lens volition in event continue in the same direction that it had when it entered the lens.

These three rules will be used to construct ray diagrams. A ray diagram is a tool used to determine the location, size, orientation, and type of image formed by a lens. Ray diagrams for double convex lenses were drawn in a previous part of Lesson v. In this lesson, nosotros volition come across a similar method for constructing ray diagrams for double concave lenses.

Pace-by-Pace Method for Cartoon Ray Diagrams

The method of drawing ray diagrams for a double concave lens is described below.

one. Option a point on the top of the object and draw three incident rays traveling towards the lens.

Using a straight edge, accurately depict one ray so that information technology travels towards the focal indicate on the opposite side of the lens; this ray will strike the lens before reaching the focal point; stop the ray at the betoken of incidence with the lens. Draw the second ray such that it travels exactly parallel to the principal centrality. Draw the 3rd ray to the exact center of the lens. Place arrowheads upon the rays to indicate their direction of travel.

2. One time these incident rays strike the lens, refract them co-ordinate to the 3 rules of refraction for double concave lenses.

The ray that travels towards the focal bespeak will refract through the lens and travel parallel to the main axis. Use a straight border to accurately draw its path. The ray that traveled parallel to the main axis on the manner to the lens will refract and travel in a management such that its extension passes through the focal point on the object's side of the lens. Marshal a direct edge with the point of incidence and the focal point, and depict the second refracted ray. The ray that traveled to the exact center of the lens will continue to travel in the same direction. Place arrowheads upon the rays to bespeak their management of travel. The three rays should be diverging upon refraction.

3. Locate and mark the image of the tiptop of the object.

The prototype point of the top of the object is the signal where the three refracted rays intersect. Since the three refracted rays are diverging, they must be extended backside the lens in order to intersect. Using a straight edge, extend each of the rays using dashed lines. Depict the extensions until they intersect. All iii extensions should intersect at the aforementioned location. The point of intersection is the image betoken of the top of the object. The 3 refracted rays would appear to diverge from this indicate. This is merely the point where all low-cal from the summit of the object would appear to diverge from after refracting through the double concave lens. Of course, the balance of the object has an image as well and it tin can be establish past applying the aforementioned three steps to another chosen point. Meet notation below.

4. Repeat the process for the bottom of the object.

The goal of a ray diagram is to determine the location, size, orientation, and type of epitome that is formed by the double concave lens. Typically, this requires determining where the image of the upper and lower extreme of the object is located and so tracing the entire epitome. After completing the first three steps, only the epitome location of the top extreme of the object has been establish. Thus, the process must be repeated for the point on the bottom of the object. If the bottom of the object lies upon the chief centrality (as information technology does in this example), then the prototype of this point will too lie upon the principal axis and be the aforementioned distance from the lens every bit the image of the tiptop of the object. At this point the complete epitome can be filled in.

Some students accept difficulty understanding how the entire paradigm of an object can be deduced once a single point on the image has been determined. If the object is but a vertical object (such as the arrow object used in the example below), then the procedure is easy. The prototype is merely a vertical line. This is illustrated in the diagram below. In theory, information technology would be necessary to pick each signal on the object and describe a separate ray diagram to determine the location of the image of that signal. That would require a lot of ray diagrams as illustrated in the diagram below.

Fortunately, a shortcut exists. If the object is a vertical line, then the paradigm is besides a vertical line. For our purposes, nosotros will only bargain with the simpler situations in which the object is a vertical line that has its lesser located upon the principal axis. For such simplified situations, the paradigm is a vertical line with the lower extremity located upon the principal axis.

The ray diagram to a higher place illustrates that the image of an object in front of a double concave lens volition be located at a position behind the double concave lens. Furthermore, the paradigm will be upright, reduced in size (smaller than the object), and virtual. This is the blazon of information that we wish to obtain from a ray diagram. The characteristics of this image will be discussed in more than particular in the next section of Lesson five.

Your Turn to Practise

Once the method of drawing ray diagrams is practiced a couple of times, it becomes as natural equally breathing. Each diagram yields specific data well-nigh the image. It is suggested that y'all take a few moments to practice a few ray diagrams on your own and to depict the characteristics of the resulting image. The diagrams beneath provide the setup; you must only describe the rays and identify the epitome. If necessary, refer to the method described above.

We Would Similar to Advise ...

Why simply read about it and when you could exist interacting with it? Collaborate - that's exactly what y'all do when you use one of The Physics Classroom's Interactives. We would like to suggest that you lot combine the reading of this page with the utilize of our Eyes Bench Interactive. You can find this in the Physics Interactives department of our website. The Eyes Demote Interactive provides the learner an interactive enivronment for exploring the germination of images past lenses and mirrors. Its like having a complete optics toolkit on your screen.