![]() ![]() Using the similar triangles ABC and EDC, it can also be seen that the distance from the object to the mirror is the same as the distance from the image to the mirror. What you notice is that the reflected rays diverge from the mirror they must be extended back to find the place where they intersect, and that's where the image is.Īnalyzing this a little further, it's easy to see that the height of the image is the same as the height of the object. Note that the reflected rays obey the law of reflection. The image will be found where the reflected rays intersect. In a ray diagram, rays of light are drawn from the object to the mirror, along with the rays that reflect off the mirror. To figure out where the image of this object is located, a ray diagram can be used. ![]() ![]() It's relatively straight-forward geometry, all based on similar triangles, but we should review that for a plane mirror.Ĭonsider an object placed a certain distance in front of a mirror, as shown in the diagram. This also implies that an image could not be focused on a screen placed at the location where the image is.ĭealing with light in terms of rays is known as geometrical optics, for good reason: there is a lot of geometry involved. the image is a virtual image, as opposed to a real image, because the light rays do not actually pass through the image.the image is the same distance from the mirror as the object appears to be (i.e., the image distance = the object distance).the image is the same size as the object (i.e., the magnification is m = 1).Images produced by plane mirrors have a number of properties, including: All objects obey the law of reflection on a microscopic level, but if the irregularities on the surface of an object are larger than the wavelength of light, which is usually the case, the light reflects off in all directions.Ī plane mirror is simply a mirror with a flat surface all of us use plane mirrors every day, so we've got plenty of experience with them. Most objects exhibit diffuse reflection, with light being reflected in all directions. All the light travelling in one direction and reflecting from the mirror is reflected in one direction reflection from such objects is known as specular reflection. Reflected light obeys the law of reflection, that the angle of reflection equals the angle of incidence.įor objects such as mirrors, with surfaces so smooth that any hills or valleys on the surface are smaller than the wavelength of light, the law of reflection applies on a large scale. Objects can be seen by the light they emit, or, more often, by the light they reflect. In particular, we'll use rays and wave fronts to analyze how light interacts with mirrors and lenses. Rays and wave fronts can generally be used to represent light when the light is interacting with objects that are much larger than the wavelength of light, which is about 500 nm. If the source is a long way away, the wave fronts can be treated as parallel lines. For a source like the Sun, rays radiate out in all directions the wave fronts are spheres centered on the Sun. A wave front is the line (not necessarily straight) or surface connecting all the light that left a source at the same time. A ray is a thin beam of light that travels in a straight line. Light is a very complex phenomenon, but in many situations its behavior can be understood with a simple model based on rays and wave fronts. ![]()
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