Be sure the object and the screen are at least one meter apart. Theory analysis of the geometry in ray diagrams for spherical curved mirrors and thin concave and convex lenses give us a relationship between the position of the object s, the position of the. Using these rules we can find the position and properties of the image. Find the focal length of a convex mirror using a convex lens. To investigate the image formed by a certain thin convex lens and to determine its focal length. A transparent material bound by two surfaces, of which one or both surfaces are spherical, forms a lens. Calculate the focal length of the convex lens by using the formula given.
Convex lenses geometric optics physics khan academy duration. Also notice that the image distance is a positive one. Using the first biconvex lens to form a magnified real image, in what range should the object distance be. Focal length of convex mirror experiment study page. Since converging lenses have positive focal lengths and diverging lenses have negative focal lengths, the power of a lens is positive for converging lenses and negative for diverging lenses.
In this experiment, we have chosen two methods to find out the focal length of a spherical lens. Convex lenses, geometrical optics from alevel physics tutor. They come together at a point called the principal focus. This is to give the student a fair idea as to how the lens equation with the measured quantities can be manipulated to obtain the focal length of the lens and also use the graphical method to determine the focal length of a lens. Repeat the measurement by adjusting the distance between lamphousing and the screen s to roughly about 5.
When parallel light rays pass through a thin lens, they emerge either converging or diverging. It shows that the rays diverge when passed through such a lens. The light rays will then refract as they pass through the lens and, for a converging lens. If those surfaces are bent outwards, the lens is called a biconvex lens or simply convex lens. It is made by light from an object passing through a converging lens as shown in figure 1.
By contact method with a convex lens of known focal length. Move the screen about 15 cm farther from the object than before, and then shift the diverging lens to produce a sharp image on the screen. All four types of convex lens are converging lenses. A convex lens gives a real, inverted image if the object is outside the focal length of the 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.
A converging lens always has two focal points, the primary focal point on the near side of the lens towards the oncoming light rays and a secondary focal point on the far side of the lens away from the oncoming light rays. Convex and concave lenses purpose in this experiment, you will explore the difference between convex and concave lenses and determine their focal lengths. Cbse physics lab manual for class 10 pdf download 4. Concave lenses geometric optics physics khan academy khan academy. A converging convex, positive lens is thicker in the center than at the edges. Experiment 3 lenses and images who shall teach thee, unless it be thine own eyes. Measure the image distance and the object distance. With a converging lens, paraxial rays that are parallel to the principal axis converge to the focal point, f. To observe newton rings formed by the interface of produced by a thin air film and determine the radius of curvature of a planoconvex lens. Dec 10, 2010 concave lenses geometric optics physics khan academy khan academy. The point where the converging rays or their extensions cross is the focal point of the lens. Record p, q, and hi for four different relative positions of the object, lens and image screen. Cbse class 10 science lab manual focal length of concave. Apparatus and material required an optical bench, two sharpedged needle pins, convex lens of less than 20 cm focal length, three uprights with clamps, index needle may be a knitting needle, metre scale and spirit level.
Repeat the experiment by moving the convex lens towards the object by 2 cm each time and record the values in a tabular column. Measure the focal length from the center of the convex lens to the focal point. In this experiment, you will explore the difference between convex and concave lenses and determine their focal lengths. Ill be the object in this video and you need to find my image. It will give a virtual upright image if the object is within the focal length. If the lens is biconvex or planoconvex, a collimated beam of light passing through the lens converges to a spot a focus behind the lens. If the convex lens selected for the experiment has focal length less. We will find that the light gets scattered on the paper after passing through the concave lens.
The relation between u, v and f for a convex lens is. In this lab, the object, lens holder, and screen are placed on track and can move along the track. Experiment 9 mirrors and lenses in this experiment you will learn to determine the focal lengths of mirrors and lenses. Report these and other data in a nicely crafted table.
A convex lens is thicker in the middle than it is at the edges. Theory lenses are frequently found in both nature and technology, wherever it is useful to form an image. It is this type of lens that is most commonly used in corrective lenses. Dec 08, 2018 eight important differences between convex and concave lens are compiled in the article in tabular form. The lens is set up in a suitable holder with a plane mirror behind it so that light passing through the lens is reflected back again fig. A lens with one convex and one concave side is convexconcave or meniscus. Jun 26, 2016 experiments to measure the focal length of a converging lens method 1. The collimator has an adjustable rectangular slit at one end and a convex lens at the other end. In this experiment, the formation of images by concave and convex lenses will be explored. A convex mirror always forms virtual image of a real object and hence the value of v i. This report presents a lab experiment that hopes to introduce and familiarise. The convex lens is delighted to be one of the companies preferred in the latest round of sbir innovation contracts awarded by smart dublin. The bouncing back of light on hitting any mediumsurface is called reflection of light.
The focal length of a convex lens experiments to measure the focal length of a converging lens method 1. Ray box with illuminated object, white screen, lens holder, metre rule and lens background the purpose of the experiment is to study image formation by a thin lens. Set the distance between the crossthreads and lens to a measured value object distance greater than the. Setup the lens apparatus as shown in figure 3, using the convex lens.
The purpose of this experiment is to verify the thin lens equation and to construct simple optical systems using various combinations of lenses. Thin lenses 127 rays of light from a nearby object will arrive at the lens at various angles. Determination of the focal length and the power of a converging. The purpose of this experiment is to determine the focal length of a thin converging lens. Because the object is further from the lens than the focal point, the image will be real. A lens bound by two spherical surfaces bulging outwards is called a biconvex lens or simply a convex lens. In particular we will find the focal length of a lens converging using the lens equation. Theory when parallel light rays pass through a thin lens, they emerge either converging or diverging. The application of the thin lens equation and the magni.
Now, mount the diverging lens on the optical bench between the converging lens and the screen as shown in fig. You will also verify the mirror and lens equation and the magnification formula by direct. A thin convex lens can be characterized by its focal length f, the object distance, d o. To find the focal length of a convex mirror using a convex lens. The converging lens is thicker at its center than at its edge. Lenses produce different types of images, depending on the position of the object relative to the lens and its focal point.
Lab preparation the picture on the screen in a movie theater is called a real image. Materials required a concave mirror, a mirror holder, a small screen fixed on a stand, a measuring scale and a distant. Convex lens is a transparent curved device that is used to refract light. To determine the focal length of converging lens and its radius of curvature. Concave lenses geometric optics physics khan academy. If we replace the convex lens with a concave lens in the above experiment of sunlight and paper. Eight important differences between convex and concave lens are compiled in the article in tabular form. Prelab quiz phys 224 thin lens and image formation. Most devices that control light have one or more lenses in them some use only mirrors, which can do most of the same things that lenses can do. Have you ever used a lens to cast an image on a wall. Light ray rules for convex lens and concave lens are discussed. On the optical bench, position the lens between a light source the object and a screen. In the experiment, we need to produce a parallel beam of rays to be incident on the prism.
Jan 17, 2020 ncert class 10 science lab manual focal length of concave mirror and convex lens. These type of lenses can converge a beam of light coming from outside and focus it to a point on the other side. Difference between convex and concave lens with figure. How do convex and concave lenses compare to each other. Convex lens, optical bench, light source, target image slide, lens mounts, and screen. A single piece of glass that curves outward and converges. The relationship between object distance o, image distance i, and lens focal length, f. Investigate the relationship between power and focal length. Aim the experiment is to enable students to physically observe the image produced by the lens. For example, a converging lens with a focal length of one meter has a power of one diopter 1 diopter 1m1.
Materials required a concave mirror, a mirror holder, a small screen fixed on a. Metre rule x 1, white screen x 1, lamp housing x 1, convex lens x 1 form the image of the object from lamp housing on the white screen by the spherical convex lens. Determination of focal length of a converging lens and mirror. Traveling microscope, sodium vapour lamp, planoconvex lens, plane. Bc objectives to examine the nature and location of images formed by lenses. Finding the focal length of a lens using the ray box. Simulator procedure as performed through the online labs. For the rays shown in figures 12, light is assumed to be coming from the left, and going toward the right.
Traveling microscope, sodium vapour lamp, planoconvex lens, plane glass plate, magnifying lens. Measure the approximate focal length of the lens by focusing a distant object onto a screen and measuring the distance. Cbse physics lab manual class 10 chapters wise download here in pdf format. Mar 03, 2019 light ray rules for convex lens and concave lens are discussed. Finally, the image distance is larger than the object distance. To measure the focal length of a converging lens using various methods and to study how a converging lens forms a real image. 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 l5. Physics practical class 10 introduction light shows the property of reflection and refraction.
These physics lab manual may be freely downloadable and used as a reference book. Have you ever used a magnifying lens to look at things far away. Conversely, the concave lenses are thinner at the centre and thicker at its edges, in structure. You will also verify the mirror and lens equation and the magnification formula by direct measurement of the positions of object and image. Ncert class 10 science lab manual image formation by a. Teacher packs in experimental science phy pack 5 finding the. In this experiment, we will be dealing only with thin lenses. Because of its ability to focus light a converging lens can produce an image of an object, as represented in fig. Repeat the experiment by using convex mirrors of different focal lengths with the help of the same convex lens. Hence lenses of such type are known as a diverging lens.
Therefore, convex lens is used to enable us to form a real image due to the combination. A lens is a piece of transparent material bound by two surfaces of which at least one is curved. This means that it is on the other side of the lens and is therefore a real image. Ncert class 10 science lab manual image formation by a convex lens practical. Thin lenses and optical instruments university of calgary. One such difference is the structure of convex lens is like, thicker at the centre and thinner at the edges.
Ncert class 10 science lab manual focal length of concave. Where f is the focal length, u is the distance between the object and. To find the focal length of a convex lens by plotting graphs between u and v or between 1u and 1v. Experiment aim to find the focal length of a convex lens by plotting graphs between u and v or between 1 u and 1 v. Jan 18, 2020 contents1 ncert class 10 science lab manual image formation by a convex lens practical1. Watch your students become scientists as they dig into these fascinating questions. Record the position of divergence lens and new position of the screen in table 2. To insert the convex lens in front of the wire gauze, click on the insert convex lens button.
Cbse class 10 science lab manual focal length of concave mirror and convex lens experiment 4a aim to determine the focal length of concave mirror by obtaining the image of a distant object. A common experimental setup for a lens experiment is shown in figure 3. Where f is the focal length, u is the distance between the object and the lens v is the distance between the image and the lens. To find the focal length of a convex lens by plotting. Lenses produce different types of images, depending on. Move the lens to a position where an image of the object is formed on the screen. It can be used to focus parallel light rays and form a real image as the light. Ncert class 10 science lab manual image formation by a convex. This point is known as the focus and the distance between the centre of the lens to the focus is called the focal length of convex lens. How will the result change if a convex lens of different refractive indices were used. Lenses lenses refract light in such a way that an image of the light source is formed. Measure the approximate focal length of the lens by focusing a distant object onto a screen and measuring the distance from the lens to the screen using the metre stick. For a double convex lens with symmetric lens concavity, such as the one in the picture and the ones you will use in the laboratory and are the same distance from the center of the lens. Focal length of a lens the following website should be accessed before coming to class.
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