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# focal length of concave mirror experiment

(b) Determination of approximate focal length of the mirror. Record your observations in observation table. As the distance between the pole 0 of the concave mirror and the focus F is the focal length of the concave mirror. Lets see the above shown diagram, Focal Length – The space between the pole P of concave mirror and the focus F is the focal length of concave mirror. Comparing above equation with standard equation of a straight line, y = mx + c, graph between 1/v and 1/u should be a straight line with a slope of (–1) and intercepts on y-axes equal to (1/f), From this you can find the focal length of the given mirror. Repeat the experiment two or three times and find the mean value of the focal length.​, Measure the distance between the concave mirror and the screen with given metre scale. Reciprocal of it gives the focal length. Read the position of its two ends, avoiding error due to parallax. Fix the mirror in mirror-holder and adjust the tips of the pins so that they are in the same horizontal line as the pole of the mirror. Drag the screen by clicking on point A of the screen till you get a sharp image of the object. The selected object should be visible with your naked eyes. Calculate the focal length of the given concave mirror by using the relation, f = uv/(u+v). (c) Determination of v for different values of u. We use mirror formula for the determination of focal length. 7. Lam Ka Yue Kenneth 6S (20) Date of experiment : 27/10/2005 Figure (5) 3. 4. Using knitting needle, adjust the object-pin, so that the distance between the pole of the mirror and the tip of the pin is l. Now read the position of the mirror arid the object-pin A, on the scale of the optical bench. 11. This measured distance is focal length of concave mirror. 3. Take the mean of the measured focal length. Measure the distance between the mirror and the wall with the help of a metre scale. Find the length of the knitting needle l. 2. Repeat the process two or three times. asked Jan 22, 2019 in Physics by kajalk ( 77.6k points) ray optics Measure the distance between the concave mirror and the screen with given metre scale. Thus, the focal length of a concave mirror can be estimated by obtaining a real image of a distant object at its focus. Repeat the measurement by adjusting the distance between lamp-housing and the screen (s) to roughly about 5.4F, 5.8F, 6.2F and 6.6F. 9. Repeat the same procedure for image pin B also. screen fixed on a stand or a white wall, an object (candle) and a metre scale. Developed by Amrita University & CDAC Mumbai. मराठी. 6. Find the values of 1/u and 1/v for each observation, by taking u and v in metres. 2 The place where the five refracted rays cross each other is the focal point of the lens. Read the intercept on y-axis. Place the other two uprights holding pins on the optical bench at different positions. A short linear object, of length I, lies along the axis of a concave mirror of focal length f, at a distance d from the pole of the mirror. Repeat the procedure for different positions of pin A between f1 and 2f1 and seeing that it is enlarged. 2. 14. \(\frac { 1 }{ f } =\frac … (b) its virtual image is formed 20cm from the mirror? Take out the mirror from mirror-holder and hold it in such a way so that a clear distinct image of a distant object is obtained on the wall. 8. This gives the approximate focal length, f1 of the mirror. Record the observations in tabulated form. 1. A concave mirror should be always placed near an open window. Find bench correction (l–l1) for pin A. Precautions. Measure the focal length from the center of the convex lens to the focal point. 10 cm is the focal length of the concave mirror. As performed in the simulator. 5. Fix the object-pin A at a point between, f1 and 2f1 but so that looking into the mirror, you will see a clear real, inverted and highly enlarged image of A. In an experiment to determine the focal length (f) of a concave mirror by the u-v method, a student places the object pin A on the principal axis at a distance x from the pole p. The student looks at the pin and its inverted image from a distance keeping his/her eye in line with PA. 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). The polished surface of the concave mirror and the distinct object should be facing each other. Focal Length of Concave Mirror Formula. In an experiment to find the focal length of a concave mirror, a graph is drawn between the magnitudes of u and v. The graph looks like : ... At what distance from a concave mirror of focal length 10cm should an object be placed so that: (a) its real image is formed 20 cm from the mirror? 4. A concave mirror is a mirror that has an inside curvature which may affect how someone would look at the mirror and how the object is reflected from that mirror. Following are the materials required for this experiment: An optical bench with three uprights; A concave mirror; A mirror holder; Two optical needles; A knitting needle; A half-metre scale; Theory. 12. 15. CBSE Class 10 Science Lab Manual – Focal Length of Concave Mirror and Convex Lens EXPERIMENT 4(a) Aim To determine the focal length of concave mirror by obtaining the image of a distant object. Materials Required A concave mirror, a mirror holder, a small … Find the observed length of knitting needle as measured on the optical bench-scale, l1. Fix concave mirror to mirror holder and place it on table.Turn the face of mirror towards a distant object (a candle in this case). മലയാളം A concave mirror, a mirror holder, a white screen fixed on a stand or a white wall, an object (candle) and a metre scale. Level the optical bench with the help of spirit level and leveling screws. Calculate the focal length (f) of the concave mirror each time. By obtaining the Real image of a distant object at its focus, the focal length of the concave mirror can be estimated as shown in the diagram. 4. To obtain the position of image for a given object distance and focal length of a mirror, the following mirror formula can be used.