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A card sheet divided into squares each of size 1 mm^(3)viewedat a distance of 9 cm through a magnifying glass (a converging lens of focal length 9 cm ) held close to the eye. a. What is the magnification produced by lenas ? How much is the area of each square in the virtual image ? b. What is the angular magnification (magnifying power ) of the lens ? c. Is the magnification in (a) equalto the magnifying power in (b)? explain. |
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Answer» Solution :a .F = 10 CM, U = -9 cm `(1)/(v) - (1)/(u)=(1)/(f)` `(1)/(v)= (1)/(f) + (1)/(u) = (1)/(10) - (1)/(9) = - (1)/(90)therefore v = - 90 ` cm Linear magnification = `(v)/(u) = (-90)/(9) =10 ` Area of each square in the image = `(1 mm xx 10)^(2) = 100 mm^(2) = 1 cm^(2)` b. angular magnification - `(D)/(|u|) = (25)/(9) = 2.8 ` c. No. If the image is located near the least distance of distinct vision (v = D= 25 cm ) , the two QUANTITIES in (a) and (b) are equal . |
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