How To Make Mirror Drawing Processing

Ray Diagrams - Concave Mirrors

The theme of this unit of measurement has been that we come across an object because light from the object travels to our eyes as we sight along a line at the object. Similarly, we run into an image of an object because light from the object reflects off a mirror and travel to our eyes as we sight at the prototype location of the object. From these two basic premises, we have defined the image location as the location in space where calorie-free appears to diverge from. Ray diagrams accept been a valuable tool for determining the path taken by light from the object to the mirror to our eyes. In this department of Lesson 3, we volition investigate the method for drawing ray diagrams for objects placed at various locations in front end of a concave mirror.

To draw these diagrams, we will accept to recall the two rules of reflection for concave mirrors:

• Any incident ray traveling parallel to the principal axis on the style to the mirror will pass through the focal signal upon reflection.
• Any incident ray passing through the focal point on the manner to the mirror will travel parallel to the principal axis upon reflection.

Earlier in this lesson, the following diagram was shown to illustrate the path of calorie-free from an object to mirror to an middle.

In this diagram five incident rays are drawn forth with their respective reflected rays. Each ray intersects at the image location so diverges to the eye of an observer. Every observer would notice the same image location and every calorie-free ray would follow the constabulary of reflection. Notwithstanding only two of these rays would exist needed to determine the image location since it simply requires 2 rays to discover the intersection point. Of the five incident rays drawn, ii of them correspond to the incident rays described by our two rules of reflection for concave mirrors. Because they are the easiest and almost predictable pair of rays to draw, these will be the 2 rays used through the remainder of this lesson.

Footstep-by-Step Method for Drawing Ray Diagrams

The method for drawing ray diagrams for concave mirror is described beneath. The method is applied to the job of drawing a ray diagram for an object located across the centre of curvature (C) of a concave mirror. Nevertheless the same method works for drawing a ray diagram for any object location.

1. Pick a point on the top of the object and describe ii incident rays traveling towards the mirror.

Using a direct border, accurately draw one ray so that it passes exactly through the focal betoken on the way to the mirror. Draw the second ray such that it travels exactly parallel to the principal axis. Place arrowheads upon the rays to indicate their management of travel.

ii. Once these incident rays strike the mirror, reflect them according to the 2 rules of reflection for concave mirrors.

The ray that passes through the focal signal on the mode to the mirror will reflect and travel parallel to the chief axis. Apply a straight border to accurately depict its path. The ray that traveled parallel to the primary axis on the manner to the mirror will reflect and travel through the focal betoken. Place arrowheads upon the rays to indicate their direction of travel. Extend the rays past their signal of intersection.

iii. Mark the image of the top of the object.

The epitome point of the summit of the object is the point where the two reflected rays intersect. If your were to describe a 3rd pair of incident and reflected rays, then the third reflected ray would also pass through this point. This is merely the point where all lite from the top of the object would intersect upon reflecting off the mirror. Of grade, the rest of the object has an image as well and information technology can be found by applying the same three steps to some other chosen bespeak. (Meet note below.)

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

The goal of a ray diagram is to make up one's mind the location, size, orientation, and blazon of epitome that is formed by the concave mirror. Typically, this requires determining where the image of the upper and lower extreme of the object is located and and then tracing the entire image. Afterwards completing the outset three steps, simply the image location of the top extreme of the object has been found. Thus, the process must exist repeated for the point on the lesser of the object. If the bottom of the object lies upon the principal axis (as it does in this example), and so the image of this point volition as well lie upon the main axis and be the aforementioned altitude from the mirror as the epitome of the top of the object. At this point the unabridged image can exist filled in.

Some students accept difficulty understanding how the entire image of an object tin can be deduced in one case a single indicate on the epitome has been determined. If the object is a vertically aligned object (such as the arrow object used in the example beneath), then the process is piece of cake. The image is merely a vertical line. In theory, it would exist necessary to option each bespeak on the object and draw a separate ray diagram to determine the location of the image of that betoken. That would require a lot of ray diagrams as illustrated below.

Fortunately, a shortcut exists. If the object is a vertical line, then the epitome is also a vertical line. For our purposes, nosotros will but deal with the simpler situations in which the object is a vertical line that has its bottom located upon the principal axis. For such simplified situations, the image is a vertical line with the lower extremity located upon the principal axis.

The ray diagram above illustrates that when the object is located at a position beyond the center of curvature, the image is located at a position between the center of curvature and the focal point. Furthermore, the image is inverted, reduced in size (smaller than the object), and real. This is the blazon of data that we wish to obtain from a ray diagram. These characteristics of the epitome volition be discussed in more than particular in the next section of Lesson three.

Once the method of drawing ray diagrams is skillful a couple of times, information technology becomes as natural as breathing. Each diagram yields specific information about the image. The two diagrams beneath show how to determine image location, size, orientation and blazon for situations in which the object is located at the center of curvature and when the object is located between the center of curvature and the focal bespeak.

It should be noted that the process of constructing a ray diagram is the same regardless of where the object is located. While the result of the ray diagram (image location, size, orientation, and type) is different, the same two rays are e'er drawn. The two rules of reflection are practical in guild to decide the location where all reflected rays appear to diverge from (which for real images, is also the location where the reflected rays intersect).

In the iii cases described above - the case of the object being located beyond C, the example of the object being located at C, and the case of the object being located between C and F - light rays are converging to a point after reflecting off the mirror. In such cases, a real image is formed. Every bit discussed previously, a real image is formed whenever reflected light passes through the image location. While plane mirrors always produce virtual images, concave mirrors are capable of producing both existent and virtual images. As shown above, existent images are produced when the object is located a distance greater than 1 focal length from the mirror. A virtual epitome is formed if the object is located less than 1 focal length from the concave mirror. To see why this is so, a ray diagram can exist used.

Watch It!

A physics instructor discusses the nature of a real prototype using a phun physics demonstration.

Ray Diagram for the Formation of a Virtual Image

A ray diagram for the case in which the object is located in front of the focal point is shown in the diagram at the right. Observe that in this instance the light rays diverge after reflecting off the mirror. When light rays diverge after reflection, a virtual image is formed. As was washed with plane mirrors, the image location tin can exist institute by tracing all reflected rays backwards until they intersect. For every observer, the reflected rays would seem to be diverging from this betoken. Thus, the point of intersection of the extended reflected rays is the epitome betoken. Since light does not actually laissez passer through this point (light never travels backside the mirror), the prototype is referred to equally a virtual image. Observe that when the object in located in front of the focal point, its paradigm is an upright and enlarged image that is located on the other side of the mirror. In fact, one generalization that can exist made about all virtual images produced by mirrors (both plane and curved) is that they are always upright and always located on the other side of the mirror.

Ray Diagram for an Object Located at the Focal Indicate

Thus far we have seen via ray diagrams that a real prototype is produced when an object is located more than one focal length from a concave mirror; and a virtual epitome is formed when an object is located less than one focal length from a concave mirror (i.e., in front of F). But what happens when the object is located at F? That is, what type of image is formed when the object is located exactly one focal length from a concave mirror? Of course a ray diagram is always i tool to assist find the reply to such a question. Withal, when a ray diagram is used for this case, an immediate difficulty is encountered. The incident ray that begins from the top extremity of the object and passes through the focal point does non meet the mirror. Thus, a different incident ray must be used in order to decide the intersection point of all reflected rays. Any incident light ray would piece of work as long as it meets up with the mirror. Recall that the only reason that we take used the two nosotros have is that they can exist conveniently and easily drawn. The diagram beneath shows two incident rays and their respective reflected rays.

For the case of the object located at the focal point (F), the light rays neither converge nor diverge after reflecting off the mirror. Equally shown in the diagram above, the reflected rays are traveling parallel to each other. Subsequently, the light rays will not converge on the object's side of the mirror to grade a real paradigm; nor can they be extended backwards on the opposite side of the mirror to intersect to grade a virtual epitome. So how should the results of the ray diagram be interpreted? The answer: at that place is no image!! Surprisingly, when the object is located at the focal point, at that place is no location in space at which an observer tin can sight from which all the reflected rays appear to exist diverging. An epitome is not formed when the object is located at the focal point of a concave mirror.

We Would Similar to Suggest ...

Why just read nigh it and when yous could be interacting with it? Interact - that'due south exactly what you lot practice when y'all use 1 of The Physics Classroom's Interactives. We would like to suggest that you combine the reading of this page with the utilize of our Optics Demote Interactive or our Name That Image Interactive. Y'all can find this in the Physics Interactives section of our website. The Optics Demote Interactive provides the learner an interactive enivronment for exploring the germination of images by lenses and mirrors. The Name That Image Interactive provides learners with an intensive mental workout in recognizing the image characteristics for whatsoever given object location in front of a curved mirror.

Check Your Understanding

The diagram beneath shows ii low-cal rays emanating from the top of the object and incident towards the mirror. Depict how the reflected rays for these low-cal rays tin can exist drawn without actually using a protractor and the constabulary of reflection.

Source: https://www.physicsclassroom.com/class/refln/Lesson-3/Ray-Diagrams-Concave-Mirrors

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