An approximate focal length was found using parallel light from a distant object. Finding the focal length of a convex lens by plotting. I created the images, of the globe filament, to the screen, and measured. If you have any query regarding cbse class 12 physics ray optics and. Concave mirror optical bench, object and image pins, meter rule. Materials required a concave mirror, a mirror holder, a small screen fixed on a stand, a measuring scale and a distant. Measure u and v repeat above step at few more object distances. Comments precautions find the approximate focal length of the lens before making measurements to ensure that only real images are.
The syllabus for the practical exam is designed by cbse according to the cce guidelines. Physics mcqs for class 12 with answers chapter 9 ray. Jan 15, 2020 cbse syllabus 202021 for all subjects of class 12. Repeat the experiment for a variety of object distances, ensuring it is always greater than the approximate focal length. Cbse syllabus for class 12 science 202021 pdf 12th class. To find focal length of a concave mirror simulation. Focal length of a concave mirror science experiment. This is possible only when you have the best cbse class 12 physics study material and a smart preparation plan.
Experiment 8 focal length of a concave mirror experiment. Measure the focal length from the center of the convex lens to the focal point. Describe what happens as the needle is moved farther from the mirror. An optical bench with four uprights two fixed uprights in middle, two outer uprights with lateral movement, convex lens 20 cm focal length, convex mirror, a lens holder, a mirror holder, two optical needles, one thin, one thick a knitting needle, and a half metre scale. It is the center of the reflecting surface of the concave mirror also called vertex of mirror, generally denoted by. Get the focal length from all measurements by a taking average of calculated f or b from u versus v graph or c from versus graph. Record p and q three different relative positions of the object, mirror and image screen. When beamrays of light fall on highly polished and smooth surface, then all the rays. Determination of focal length of concave mirror and convex lens. Focal length of a concave mirror experiment class 12 cbse. To find focal length of a concave mirror procedure. To find the value of v for different values of u in case of a concave mirror and find its focal length f by plotting graph between 1u and 1v. Jan 22, 2020 mcq on ray optics class 12 question 1. Cbse physics lab manual for class 12 pdf download 7.
This fact is used in the following two methods for finding the focal length of a concave mirror. Determination of focal length of concave mirror and convex. To find the focal length of a convex lens by plotting graphs between u and v or between 1u and 1v. Repeat the experiment two more times by obtaining the images of two. How far an object should be placed from the pole of a concave mirror of focal length 20cm to form a real image whose size is 15 the. While plane mirrors always produce virtual images, concave mirrors are capable of producing both real and virtual images. To find the value of v for different values of u in case of a concave mirror and to find the focal length. Class 9th, 10th, 11th, 12th download pdf rrb ntpc 2020 updates. Repeat the experiment for different values of u up to 2. To find the focal length of a concave lens, using a convex. Dec 28, 2017 mount the concave mirror in the mirror holder. Cbse class 10 science mcqs on chapter 10 light reflection.
To find the focal length of a convex mirror using a convex lens. Focal length of convex lensb11 lab report objectives of the experiment. To find the focal length of a convex mirror using convex lens. Candidates who are ambitious to qualify the class 12 with good score can check this article for notes. Cbse class 10 science lab manual focal length of concave mirror and convex lens. Conclusions the focal length of the lens was measured to be 12. This document is highly rated by jee students and has been viewed 4507 times.
Concave mirror focal length by uv method meity olabs youtube. Concave mirrors have the reflecting surface that bulges inward. Jun 08, 2016 focal length of a concave mirror experiment class 12 cbse c. We can repeat the experiment with concave mirrors of different focal. Repeat the experiment by changing the separation between the. Sep 07, 2014 the combined focal length of one convex and one concave lenses having focal length 10 cm and 9. To determine the focal length of concave mirror by obtaining the image of. The focal length of a concave mirror is 30cm, find the position of the object in front of the mirror so that the size of the image is three times the size 879. In case, if the focal length of the given thin convex lens is not known then rough value of its focal length f l should be estimated first to ensure that its focal length is less than that of the concave lens. Experiment 8 focal length of a concave mirror experiment class 12 cbse. Cbse physics practical class xii finding the focal length. To find the value of v for different values of u in case of a concave mirror and to rind the focal length. Cbse class 10 science lab manual focal length of concave. For a curved mirror, the radius of curvature, r can be defined as the.
Before getting started with the experiment, it is important to understand a few terms that are used in a concave mirror and convex lens centre of curvature. Place the lens on the holder with fixed upright such that the upright is kept at 50 cm mark. A teacher asks rani to obtain a sharp image of distant object on the screen by choosing appropriate devices out of the following. Calculate the focal length f of the concave mirror each time. Physics mcqs for class 12 with answers chapter 9 ray optics. Its inner concave surface is polished and outer convex surface. Class xiicbsephysics ray optics and optical instruments. To find the focal length of a convex mirror, using a convex. To find the focal length of a concave lens using convex lens. Find the average value of the focal length using the first three trials. As shown above, real images are produced when the object is located a distance greater than one focal length from the mirror.
The student looks at the pin and its inverted image from a distance keeping hisher eye in line with pa. The combined focal length of one convex and one concave lenses having focal length 10 cm and 9. The cbse is a prestigious educational board in india that conducts the final examinations for the class 12. Materials required a concave mirror, a measuring scale, a screen a mirror holder and mirror stand. Use the lensmakers equation to determine the focal length of a thin lens. Concave mirror focal length by uv method meity olabs. Lets see how, since we know object is always placed on the left side or direction. To find the focal length of a convex mirror, using a. Use equation 1 or 1a, magnification using equation 2 for either trial 2 or 3. The bouncing back of light on hitting any mediumsurface is called reflection of light. Ncert class 10 science focal length of concave mirror and. A mirror whose surface is cut out of a spherical shell, is called a spherical mirror.
The focal length of the mirror is calculated as, repeat the experiment by moving the convex lens towards the object by 2 cm each time and record the values in a tabular column. 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. To find the focal length of a convex mirror, using a convex lens. Jan 12, 2018 experiment 8 focal length of a concave mirror experiment class 12 cbse. To determine the focal length of a concave mirror by obtaining image of a distant object. Use this data to determine an average value of the focal length, f, and the radius of curvature, r of the concave mirror.
In an experiment to determine the focal length f of a concave mirror by the uv method, a student places the object pin a on the principal axis at a distance x from the pole p. Measure the distance between mirror and screen rough focal length. For a curved mirror, the centre of curvature, c can be defined as the centre of a hollow glass sphere of which a curved mirror is a part. That is, all light rays that are initially parallel to the yaxis i. So on combination of the one convex and one concave lens the effective focal length increases and hence its effective power decreases. Measure the distance between the mirror and first screen and take as the radius of curvature of the mirror r. A rod of length 10 cm lies along the principal axis of a concave mirror of focal length 10 em in such a way that its end closer to the pole is 20 cm away from the mirror. Light shows the property of reflection and refraction. Dec 24, 2019 the focal length of concave mirror is taken negative and for a convex mirror taken as positive.
A converging lens is used to form an image on a screen. The uv method to find focal length of a given concave mirror or convex lens consists of following steps. For a curved mirror, the radius of curvature, r can be defined as the radius. Experiment with the laser beam direction until no light emerges at. The focal length of a concave mirror is negative and that of a convex mirror is positive. A concave mirror is that spherical mirror in which the reflection of light takes place at the concave surface i. Obtain the image of a tree or building outside of the window on a screen and move the mirror forward and backwards to get a sharp image on the screen.
For a concave mirror, the principal focus is in the front and for a convex mirror, the principal focus is at the behind. Class 12 physics ray optics get here the notes for class 12 physics ray optics. Measure the distance between the concave mirror and the screen with a metre scale. A virtual image is formed if the object is located less than one focal length from the concave. Give the location of the image and the magnification.
Jan 17, 2020 to determine the focal length of concave mirror practical i to determine focal length of a given concave mirror. This video channel is developed by amrita universitys create amrita. Focal length of a concave mirror experiment class 12 cbse c. Calculate the mean of all focal lengths to get the correct focal length of the given concave mirror. As a convex mirror always forms a virtual image, its focal length cannot be found directly as. Select a distant object from the laboratory window distance should be more than 50 ft.
Its outer convex surface is polished and inner concave surface reflects. When the upper half of the lens is covered by an opaque screen. For a concave mirror, the reciprocal of its focal length f is equal to the sum of the reciprocals of image distance v and the object distance u. Note that in step 2, the rays leaving the lens are diverging and they will not cross. This will he equal to the rough focal length of the mirror. Concave mirror retort stand 2 pins in stands candle matches ruler screen procedure. In order to determine the focal length of a concave mirror by obtaining the image of distant object on screen, the position of screen should be. To study reflection in concave mirror physics astronomy.
To find the value of v for different values of u in case of. Describe the shapes of three typical converging positive thin lenses and three typical diverging. Released download new goa ssc time table pdf from here. Repeat the experiment two or three times and find the mean value of the focal length. The lens should be placed in such a way that its surface is vertical and perpendicular to the length of the optical bench.
It can be found by obtaining a sharp image of the sun or a tree on a plane wall or on a sheet of paper, and measuring the. Drag the screen by clicking on point a of the screen till you get a sharp image of the objec t. Cbse notes class 12 physics ray optics aglasem schools. Simulator procedure as performed through the online labs. Focal length of a concave mirror science experiment, physics. To determine the focal length of a spherical convex lens by lens formula method by lens replacement method. In this experiment, we have chosen two methods to find out the focal length of a spherical lens. Determination of focal length of concave lens using convex. Ray optics and optical instruments class 12 physics mcqs pdf. Cbse ncert solutions for class 12 physics chapter 9. Determination of focal length of concave mirror experiment edunovus online smart practicals duration. To determine the rough focal length of the lens, measure the distance between the lens and the screen.
Clamp the holder with lens fixed upright at 50cm mark. Nov 30, 2016 to find the focal length of a convex mirror, using a convex lens. Determination of focal length of a converging lens and mirror. Saurabh has to perform the experiment of finding the focal length of a concave mirror by using a distant. Results controlled variables focal length of concave mirror. Mcq has become a regular feature of cbse class 12 physics question paper. Physics practical class 12 all study guide at one place. Again, begin by the identification of the known information.
They are also called converging mirrors because it converges all parallel beam of light. Measure the distance between the screen and mirror image distance. Obtain approximate value of focal length of the concave mirror by focussing the image of a distant object. For a concave mirror, the reciprocal of its focal length f is equal to the sum of the reciprocals. Focusing properties of spherical and parabolic mirrors.
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