Question

112 marks] Questions 3 The focal length of two converging lenses has been experimentally determined to be: fi = 30.0 30.5 cm and fy = 50 +0.5 cm, respectively. Show with clear calculations and reasoning which lens will project the image of an object onto a screen with a magnification ml S3, if the object distance is 60 cm. [8 marks]

Answer 1

due 3 a Data given in problem focal length of converging lense ,2 30 of 0.5 and fr 50 f 0.5 cm and object distance (denoted by u) u= 60 cm but the distance from the left side to the lenses are taken be negative. then uz – 60 Can. screen object - 50 cm Conse So we have to know which lense will project the image of object with magnification (m123 that means magnification must be 33 <33

magnification for ME = a comenging lense 0 where uz image distance uz object distance with the help of solve the expression expression - t equation (1) become mz for first lense fi= 30 +0.5 cm f = 30 cm (ignore the uncertainty for instanca) magnification of first lense ya 30 fi z 30 -30 = -1 mz 7 3060 for second 25o ay A - 50 To - 5 lense meta m -5 50-60 feu

Therefore the magniffication of first lense with focal length f, 30 +015 Can is in the range - Įm23. and the first lense will project the image onto a screen with magnification (m123.