Thin lenses physics pdf

Lens are used in making spectacles, cameras, cinema projectors, microscopes and telescopes. Diverging lens now you are going to measure the focal length of the diverging lens. Thin lenses and optical instruments equipment 1 meter optical bench with 5 moveable mounts, lighted test object, 3 lens holders, screen, 2 short focal length double convex lenses l1, e1, 2 medium focal length double convex lenses l2 and l3, 1 long focal length double convex lens l4, 1 double concave lens. Lenses are used in making spectacles, cameras, cinema projectors, microscopes and telescopes. This handout is provided as a guide to the equipment and possible measurements but students are encouraged to develop their own. To learn how to make a scale ray diagram for a combination of a positive and negative lens. There is no new physics in putting lenses in combination. Thin lenses, converging lens, diverging lens, lens equation, object. A lens is conventionally defined as a piece of glass which is used to focus or change the direction of a beam of light passing through it they are mainly made of glass or plastic. The primary goals are to understand the relationship between image distance, object distance, and image scale.

The focal length is the distance from the center of the lens to the focal point. Another important characteristic of thin lenses is that light rays that pass through the center of the lens are undeviated, as shown by light ray 2. The term thin is, of course, qualitative, and just means in this sense that we can ignore. The primary goals are to understand the relationship between. Lenses lenses are made of transparentmaterials, like glass or plastic. A thin lens is one whose thickness is negligible in comparison to the image and object distance.

The objective of this experiment is to measure the focal length of a converging lens and a diverging lens. A thin lens with spherical surfaces will give an undistorted image. Apertures control the amount of light that gets into an optical system and hence the intensity of. Apertures control the amount of light that gets into an optical system and hence the intensity of the image formed by the system. Remove the converging lens and put the diverging lens on the bench. Focal length of convex lens b11 lam ka yue kenneth 6s 20 date of experiment. The lens experimental setup consists of a light source object, converging lens and image screen. We will assume that the thickness of a lens is small compared with its focal length thin lens approximation. The light rays will then refract as they pass through the lens and, for a converging lens, form an image at a distance d i refer to fig. Determination of focal length of a converging lens and mirror. Shows how to use the thin lens equation to calculate the image distance, image height and image orientation for convex lenses when the object distance is greater the the focal length f.

You cant form a real image on a screen with just a diverging lens. Light is an electromagnetic disturbance, and as such is described using maxwells equations, which. One side of the lens is flat, and the other is convex with the radius of curvature of 30 cm. Physics 215 experiment 14 thin lenses 79 advance reading urone, chapter 24, section 246 objective. Thin lenses physics 227 lab variables relate to the diagram. Thin lenses 127 rays of light from a nearby object will arrive at the lens at various angles. Thin lens equation and problem solving video khan academy. Another way to calculate the focal length is used the imageobject equation for a thin lens. Experimental treatment required estimation method, lens formula, lens minor method.

These components are placed on a meter stick for easy position measurements. The application of the thin lens equation and the magnification. The focal length of a lens depends on the refractive index of the material of the lens n l, the refractive index of the medium in which it is immersed n m and the radii of curvature of the two faces of the lens r 1 and r 2 according to the formula valid for thin lenses. These two rules will greatly simplify the task of determining the image location for objects placed in front of converging lenses. Images with thin lenses washington state university. All lenses have 2 focal points, one on each side of the lens, but only one focal length. The thin lens equations are broadly applicable to all situations involving thin lenses and thin mirrors. Then the 2nd lens is going to create an image of that image and so what were basically going to do is were going to use the thin lens. Use raytracing techniques to locate images formed by thin lenses. Let x o denote the perpendicular distance of the object from the centerline of the lens and let x o be positive. The image distance is the distance along the axis of the lens to the image.

Lenses remembering the basics of mirrors puts you half ways towards fully understanding lenses as well. Thin lenses a very commonly used optical device is the thin lens. For the love of physics walter lewin may 16, 2011 duration. For now, internalize the meaning of the rules and be prepared to use them. Unless otherwise specified, a lens problem always assumes that you are using thin, spherical.

A lens is a piece of transparent material which is shaped so that it can produce an image by refracting light rays. Nearby object as mentioned, a diverging lens will usually form a. Ray diagrams are the best method for visualizing the formation of images by lenses. A very commonly used optical device is the thin lens. A ray is a line that has an origin, but does not have an end. Thin lenses a common experimental setup for a lens experiment is shown in figure 3. Researchers create focusfree camera with new flat lens. The focal length, when youve got a thin lens, theres a focal point on each side of the lens. To experimentally determine the focal length of a converging lens using two different methods. The application of the thin lens equation and the magni. A convex lens is thicker in the center than at the edges and can also be called a positive lens or converging lens. The same sort of rules apply, just with a few modifications. The focal length is an intrinsic property of the lens.

Long, 1992 thin lens with an aperture aperture effects are among the most vexed topics in all of geometric optics. Note that this equation is valid only for thin, spherical lenses. Finally, the magnification of a mirror or lens is given by the formula hh ss. Each of a lens two faces is part of asphere and can be convex or concave if a lens is thicker at the center than theedges, it is a convex, or converging, lenssince parallel rays will be converged tomeet at the focus. The purpose of this lab is to introduce students to some of the properties of thin lenses and mirrors. Show that in the figure opposite the lenses in the left column are convex positive f whereas the lenses in the right column are concave negative f. In optics, a thin lens is a lens with a thickness distance along the optical axis between the two surfaces of the lens that is negligible compared to the radii of curvature of the lens surfaces. Use the lensmakers equation to determine the focal length of a thin lens. The overall idea of how were going to approach is this. Keep in mind that for an object to be considered a lens it must be made of a transparent material. Practically speaking, it means we trace the rays to the center plane of the lens. Given a focal length and an object distance, you can use the thin lens equa. In the thin lens approximation, the thickness t of the lens is much, much less than the radii r 1 and r 2 of curvature of the surfaces of the lens. This topic will be discussed in the next part of lesson 5.

The imagedistance, q, is the distance between the image and the center of the lens. The focal length is the distance from the center of the lens to one of these focal points. Lecture 18 geometric optics ii thin lenses unm physics and. Lab 10 board notes thin lenses friday, may 30, 2014 9.

University of tn chattanooga physics 1040l 8302012 the purpose of a lens is to form the image of an object. These three quantities are related through the equation. A lens is made of glass with index of refraction 1. This laboratory will be performed in the discovery format. Lenses whose thickness is not negligible are sometimes called thick lenses the thin lens approximation ignores optical effects due to the thickness of lenses and simplifies ray tracing calculations.

Converging lenses the approximate focal length of a thin converging lens is the distance from the lens to a screen on which is formed the real image of a very distant object, such as the landscape seen through a window of the laboratory. A lens which is thicker at its centre than at its edges converges light and is called convex or converging lens a lens which is thicker at its edges than at its centre diverges light and is known as concave or diverging lens. Images with thin lenses goals to learn experimental techniques for determining the focal lengths of positive converging and negative diverging lenses in conjunction with the thin lens equation. The term thin is, of course, qualitative, and just means in this sense that we can ignore the thickness of the lens when ray tracing. A concave lens is thinner at the center than at the edges and can also be called a negative lens or a diverging lens. The sign of the image distance can tell you additional information on the image. Light refracts when passing through media with different indices of. Prelab quiz phys 224 thin lens and image formation. Which one, its doesnt actually matter, because if you want to know whether the focal length is positive or negative, all you have to look at is what type of. Calculate the focal length in air for a glass lens n1. Repeat the measurement by adjusting the distance between lamphousing and the screen s to roughly about 5. Engineers develop thin, lightweight lens that could produce slimmer camera phones, longerflying drones.

We also acknowledge previous national science foundation support under grant numbers 1246120, 1525057, and 14739. A lens is conventionally defined as a piece of glass which is used to focus or change the direction of a beam of light passing through it. These distances and focal lengths are related by the thin lens equation. In addition, for spherical mirrors the focal length is half the radius of curvature of the reflecting surface. State at least two possible physics sources of our percent error do not include rounding. This 1st lens is going to create an image of this object over here. Let x i denote the perpendicular distance of the image from the centerline of the lens.

The glass lens which is thicker at its center than its edge is the converging lens. In this experiment, the formation of images by concave and convex lenses will be explored. Physics notes form 4 free download kcse revision notes pdf. Illustrate the formation of images using the technique of ray tracking.