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A 10 million metre long penis placed vertically in front of a concave mirror a 5 million long images formed at a distance of 30 cm from the mirror what is the focal length of the mirror |
Answer» The focal length of the pin is 30 cm.Explanation: Correct statement: A 10 mm long awl pin is placed VERTICALLY in front of a concave mirror.A 5 mm long awl pin is formed at a distance of 30 cm in front of mirror.Find the focal length of the mirror? Solution: size of object = O = 10.0 mm = 1.0 cm (as, 1 cm = 10 mm) Size of the image = 0.5 cm Image distance(v) = −30 cm Let the object distance be u. Focal length = ?? Magnification (m)= -v/u I/O = -v/u 0.5/1 = -30/u = -60 cm By using lens mirror formula 1/f = 1/v + 1/u = 1/-30 +1/-60 = -2-1/60 = -3/60 = 20 cm Focal length(f) = 30 cm Thus the focal length of the pin is 30 cm. Also LEARN more How FAR should an object be from the pole of a concave mirror of focal length 20 cm to form a real image WHOSE size is 1/5th of the object.? |
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