question_answer 28)

A card sheet divided into squares each of size1 mm2 is being viewed at a distance of 9 cmthrough a magnifying glass (a converging lensof focal length 10 cm) held close to eye. (a) What is the magnification (image size/objectsize) produced by the lens ? How much is thearea of each square in the virtual object ? (b) What is the angular magnification(magnifying powers) of the lens ? (c) Is the magnification in (a) equal tomagnifying power in (b) ? Explain.  

Answer:

(a) Using the lens formula, when f = 10 cm, u = -9 cm, we get i.e. i.e. Linear magnification Area of each square in the image = (1 mm x 10) x (1 mm x 10) = 100 mm2 = 1 cm2 (b)Angular magnification (c) Clearly magnification and powermagnification are not equal to each otherunless the image is located near the leastdistance of distinct vision, i.e. v = D.