# focal length of concave mirror experiment

11. 9. 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. Adjust the position of the screen in such a way that it forms a clear image of the candle on the 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). Measure the distance between the mirror and the wall with the help of a metre scale. Experiment: 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 1/u and 1/v. Repeat the procedure for different positions of pin A between f1 and 2f1 and seeing that it is enlarged. 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. 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. 12. Record the result in Table 6.1. 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. 14. Read the intercept on y-axis. Find the length of the knitting needle l. 2. Position the image-pin B beyond 2f1, so that there is no parallax between the tip of B and the tip of image of A. (b) Determination of approximate focal length of the mirror. This measured distance is focal length of concave mirror. 2. 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. 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. Find the observed length of knitting needle as measured on the optical bench-scale, l1. Developed by Amrita University & CDAC Mumbai. Mirror formula is given as: $$\frac{1}{f}=\frac{1}{v}+\frac{1}{u}$$ 13. Repeat the experiment for different values of u (up to 2.5f) and in each time, measure v and record it in the tabular column. 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. Concave mirror, optical bench with three uprights, mirror holder, two pins, knitting needle, metre rod, spirit level. Level the optical bench with the help of spirit level and leveling screws. Read the position of its two ends, avoiding error due to parallax. 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). 4. asked Jan 22, 2019 in Physics by kajalk ( 77.6k points) ray optics Plot a graph with 1/u on x-axis and 1/v on y-axis, taking scone scale on both axes and start from zero on either axes. 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. Measure the distance between the concave mirror and the screen with given metre scale. Precautions. 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. Find bench correction (l–l1) for pin A. Place the other two uprights holding pins on the optical bench at different positions. To obtain the position of image for a given object distance and focal length of a mirror, the following mirror formula can be used. 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. Repeat the process two or three times. 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? (c) Determination of v for different values of u. Note that in Step 2, the rays leaving the … 2 The place where the five refracted rays cross each other is the focal point of the lens. मराठी. 10 cm is the focal length of the concave mirror. Repeat the process two or three times. 1/f = 1/v + 1/u. Calculate the focal length of the convex lens by using the formula given. We use mirror formula for the determination of focal length. Repeat the same procedure for image pin B also. 1. 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. Record your observations in observation table. 8. 7. Drag the screen by clicking on point A of the screen till you get a sharp image of the object. 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). As performed in the simulator. screen fixed on a stand or a white wall, an object (candle) and a metre scale. Funded by MeitY (Ministry of Electronics & Information Technology), English Repeat the procedure for the concave lens. Measure the focal length from the center of the convex lens to the focal point. (b) its virtual image is formed 20cm from the mirror? Materials Required A concave mirror, a mirror holder, a small … To get a well illuminated and distinct image of the distinct object, the distant object should be well illuminated. The polished surface of the concave mirror and the distinct object should be facing each other. Measure the distance between the concave mirror and the screen with a metre scale. 3. This measured distance is. Fix the mirror again in the mirror-holder. हिंदी 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. Calculate the focal length (f) of the concave mirror each time. As the distance between the pole 0 of the concave mirror and the focus F is the focal length of the concave mirror. Lam Ka Yue Kenneth 6S (20) Date of experiment : 27/10/2005 Figure (5) 3.