Problem an object is placed at 2f to the left of a diverging length of focal length 10 cm. A convex lens gives a real, inverted image if the object is outside the focal length of the lens. Lenses in optics applications types of lenses physics. The magnitude of the mirror s radius of curvature is 20. Ifthe outside, or convex surface, is silvered, we have a convex mirror. The physics convex lenses are converging lenses, and concave lenses are diverging lenses. Youngs doubleslit diffraction experiment for light and some laser tricks, too doc physics duration. Patents for nonreversing mirrors go back as far as 1887, when john derby created one by placing two mirrors perpendicular to each other source. Reflection from spherical mirrors kindle education. Mirrors are used widely in optical instruments for gathering light and forming images since they work over a wider wavelength range and do not have the problems of dispersion which are associated with lenses and other refracting elements. Acoustic mirrors are huge concrete dishes built to reflect and distribute sound instead of light. In 1678 the great dutch physicist christian huygens 16291695 wrote a treatise. For each object position, answer the following questions about the. The law of reflection says that when a ray of light hits a surface, it bounces in a certain way, like a tennis ball thrown against a wall.
The distance from the center of the lens to the focal point is the lenss focal length f. This property has put mirrors and lenses in use for centuries. Geometric optics converging lenses and mirrors mercer. The bausch and lomb optical company has reported completion of a special project of nearly two years duration for the astrophysics laboratory of the vaticans observatory. In describing mirrors and lenses, the word object is used in a new way. It is proven in introductory physics textbooks1 that the image and.
Images in concave mirrors appear upside down, real and reduced. Should that not be a minus sign on the left hand side. The difference between mirror and lens is that mirror means a smooth and highly polished glass surface, through which images are formed by reflection, as the light falls on it. There are two types of lenses, and they each change the perspective of how things look. Mirrors and lenses reflection we describe the path of light as straightline rays reflection off a flat surface follows a simple rule. A person is sitting in front of two mirrors that intersect at a right angle. Pdf optical images due to lenses and mirrors researchgate. A lens is a curved piece of glass or plastic designed to refract light in a specific way. Geometric optics converging lenses and mirrors physics lab iv objective in this set of lab exercises, the basic properties geometric optics concerning converging lenses and mirrors will be explored. Using a ruler or other straight edge and the ray tracing methods described in this section, locate and draw the image of the pencil.
When light hits a surface at a low angle like on a lake at. One of the easiest shapes to analyze is the spherical mirror. In both cases, the object distance is less than the focal distance. Sells, elementary classical physics allyn and bacon, boston, 1973, second edition, vol. Mirrors reflect light and create images in a way similar to a lens, depending on where an object is located in relation to a mirror. The focal length, f, is the distance between f and the lens. In this set of lab exercises, the basic properties geometric optics concerning converging lenses and. So lets see how it goes, suppose that ive got an object out here in air and then ive got a piece of glass thats curved outward like this in a convex way. Spherical mirrors problems the physics hypertextbook. University physics 227n232n mirrors and lenses todd satogata. We use your linkedin profile and activity data to personalize ads and to show you more relevant ads. As of 2010, mirrors and lenses are so prevalent that most people use them every day, regardless of whether or not they consciously perceive the use. They are used in telescopes to help view items that are far away and are used in.
The focal lengths of convex mirrors and diverging lenses that always produce virtual images are negative. Image 1 is a single reflection image from mirror 1. In addition, for spherical mirrors the focal length is half the radius of curvature of the reflecting surface. One characteristic feature of all thin lenses and concave mirrors is the focal length, f, and is defined as the image distance of an object that is positioned infinitely far way. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext.
In order to understand mirrors, we first must understand light. Lenses remembering the basics of mirrors puts you half ways towards fully understanding lenses as well. A convex lens is thicker in the middle than on its outside edge. Homework resources in mirrors and lenses physics science. Finally, the magnification of a mirror or lens is given by the formula hh ss where h is. Biconvex glass lens, spherical concave mirror, meter ruler, optical bench, lens holder, selfilluminated object generally a vertical arrow, screen. Note the location, orientation upright or inverted, relative size larger or smaller than object.
You need only two rays to determine where an image is. It will give a virtual upright image if the object is within the focal length. A magnifying glass is a convex lens that lets the observer see a larger image of the object being observed. Sign convention for spherical mirrors and thin lenses. Homework statement the object in the figure below is midway between the lens and the mirror, which are separated by a distance d 24. Image formation in a concave mirror place an object before a concave mirror for each of the following object positions shown below and obtain its image. However, when you move closer to the mirror, the image enlarges moving closer to the mirror rightside up, virtual image. Concave mirrors curve inward, creating a focal point in front of the mirror.
In the gaussian method the same equation is used for mirrors and lenses. The primary goals are to understand the relationship between image distance, object distance, and image scale. In the two situations shown, the mirrors have the same focal lengths, and the object distance from the mirror to the arrow is the same. A lens can focus light to form an image, unlike a prism, which refracts light without focusing. If the object and image are the same distance from the mirror and magnification is 1, then as the object approaches the mirror at a certain speed, the image is approaching the plane mirror at the same speed, therefore you approach the image more quickly than you approach. On the other extreme, a lens is a part of transparent refracting medium, i. In this video i will introduce the objects, focal points, images of the converging and diverging lenses, and concave and convex mirrors. The same sort of rules apply, just with a few modifications. The most apparent distinction between mirrors and lenses are that mirrors reflect light rays light bounces back while light rays are refracted passthrough through a lens. Or should it be a plus sign for mirrors and minus for lenses. The focal lengths of a biconvex lens and a concave mirror are shown in figures 1 and 2, respectively. Typically such a mirror is not a complete sphere, but a spherical cap a piece sliced from a larger imaginary sphere with a single cut. This means that light rays are reflected with equal angles of incidence and reflection. Concave converging mirror top and convex diverging mirror bottom.
Researchers have, however, created thin, structured sheets that, when placed over a normal flat mirror, disturb the passage of light and cause it to be reflected at any desired angle 1. An expanded view of the path taken by ray 1 shows the perpendiculars and the angles of incidence and refraction at both surfaces. General physics ii course lecture notes section xii. Just how much do you know about the different types of lenses and mirrors.
Rays of light entering a converging lens parallel to its axis converge at its focal point f. Lenses are used in glasses and contacts to help correct vision. Lenses lenses refract light in such a way that an image of the light source is formed. Apply the thinlens equation and the mirror equation to determine the focal length of a converging lens and mirror. The purpose of this lab is to introduce students to some of the properties of thin lenses and mirrors. Mirrors and lenses both have the ability to reflect or refract light. Image 2 is a single reflection image from mirror 2. Congratulations to bingyi wang 18 and will kirby 17. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Drawing the ray diagrams is an ideal way to illustrate the formation of images by spherical mirrors.
With a converging lens, paraxial rays that are parallel to the principal axis converge to the focal point, f. The task involved production of four identical six. The incoming angle, called the angle of incidence, is always equal to the angle leaving the surface, or the angle of reflection. The english military used them before the invention of radar as an early warning system against air. Choose your answers to the questions and click next to see the next set of questions. A mirror will have only one focal point, which is in front of the mirror.
A spherical mirror consists of a small section of the surface of a sphere with one side of the surface covered with a polished reflecting material, usually silver or aluminum. Plane mirrors science and mathematics education research group supported by ubc teaching and learning enhancement fund 20122014 department of curriculum and pedagogy a place of mind f a c u l t y o f e d u c a t i o n. Unscramble the shaded letters to find the name of the man who placed a mirror on the moon so that scientists can measure its distance from the earth. In this trivia questions quiz, you will get to learn some more about the different lenses and mirrors and how they differ from each other. Difference between mirror and lens with comparison chart. The goal of the experiment is to be able to analyze ray diagrams so as to determine fundamental properties of image formation. Use raytracing techniques to locate images formed by thin lenses.
The image distance for a plane mirror is always equal to the object distance because the magnification is 1. Mirrors are typically flat, metalcoated sheets that reflect all incoming light waves at an angle that is equal but opposite to the incident angle. Determination of focal length of a converging lens and mirror. Light parallel to the principal axis a converges toward f after reflection from a concave mirror, and b diverges from f after reflection from a convex mirror. Keep in mind that for an object to be considered a lens it must be made of a transparent material. Most mirrors used commercially are made of glass, with the rear surface silvered and then coated with a layer of paint or lacquer for protection.
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