Diverging Lenses - Object-Image Relations
The graphical method of locating the image produced by a concave mirror consists of drawing light-rays emanating from key points on the object, and finding. The radius of curvature r, which is positive for concave mirrors and negative for convex Figure 3 shows examples of the two types of images. How to find the . to be one.) The relation between the object and the image can be understood. (You can compare this with the plane mirror image above. also produce virtual and upright images for short object distances. Two examples showing virtual, upright, diminished images in convex mirrors.
Light rays actually converge at the image location. If a sheet of paper were placed at the image location, the actual replica of the object would appear projected upon the sheet of paper.
The object is located at C When the object is located at the center of curvature, the image will also be located at the center of curvature. In this case, the image will be inverted i. The image dimensions are equal to the object dimensions. A six-foot tall person would have an image that is six feet tall; the absolute value of the magnification is equal to 1. As such, the image of the object could be projected upon a sheet of paper. The object is located between C and F When the object is located in front of the center of curvature, the image will be located beyond the center of curvature.
Regardless of exactly where the object is located between C and F, the image will be located somewhere beyond the center of curvature.Object image and focal distance relationship (proof of formula) - Physics - Khan Academy
The image dimensions are larger than the object dimensions. A six-foot tall person would have an image that is larger than six feet tall; the absolute value of the magnification is greater than 1. The object is located at F When the object is located at the focal point, no image is formed. As discussed earlier in Lesson 3light rays from the same point on the object will reflect off the mirror and neither converge nor diverge. After reflecting, the light rays are traveling parallel to each other and do not result in the formation of an image.
The object is located in front of F When the object is located at a location beyond the focal point, the image will always be located somewhere on the opposite side of the mirror.
Image Characteristics for Convex Mirrors
Regardless of exactly where in front of F the object is located, the image will always be located behind the mirror. In this case, the image will be an upright image. That is to say, if the object is right side up, then the image will also be right side up.
In this case, the image is magnified; in other words, the image dimensions are greater than the object dimensions. A six-foot tall person would have an image that is larger than six feet tall; the magnification is greater than 1.
Finally, the image is a virtual image. Light rays from the same point on the object reflect off the mirror and diverge upon reflection. For this reason, the image location can only be found by extending the reflected rays backwards beyond the mirror.
Diverging Lenses - Object-Image Relations
The point of their intersection is the virtual image location. It would appear to any observer as though light from the object were diverging from this location. Any attempt to project such an image upon a sheet of paper would fail since light does not actually pass through the image location. It can be seen that the reflected rays all come together at some point.
Thus, is the image of i. As is easily demonstrated, rays emanating from other parts of the object are brought into focus in the vicinity of such that a complete image of the object is produced between and is the image of point. This image could be viewed by projecting it onto a screen placed between points and. Such an image is termed a real image. Note that the image would also be directly visible to an observer looking straight at the mirror from a distance greater than the image distance since the observer's eyes could not tell that the light-rays diverging from the image were in anyway different from those which would emanate from a real object.
According to the figure, the image is inverted with respect to the object, and is also magnified. Formation of a real image by a concave mirror. In this case, the image appears to an observer looking straight at the mirror to be located behind the mirror.
Object image and focal distance relationship (proof of formula) (video) | Khan Academy
For instance, rays emanating from the tip of the object appear, after reflection from the mirror, to come from a point which is behind the mirror. Note that only two rays are used to locatefor the sake of clarity.
In fact, two is the minimum number of rays needed to locate a point image. Of course, the image behind the mirror cannot be viewed by projecting it onto a screen, because there are no real light-rays behind the mirror.
This type of image is termed a virtual image. The characteristic difference between a real image and a virtual image is that, immediately after reflection from the mirror, light-rays emitted by the object converge on a real image, but diverge from a virtual image. Formation of a virtual image by a concave mirror. The graphical method described above is fine for developing an intuitive understanding of image formation by concave mirrors, or for checking a calculation, but is a bit too cumbersome for everyday use.
The analytic method described below is far more flexible.