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InterviewSolution
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A concave convex figure lens made of glas `(mu=1.5)` has surface of radii 20 cm and 60 cm. a. Locate the image ofan object placed 80 cm to the left of the lens along the principal axis. B. A similar lens is placed coaxially at distanc of 160 cm right of it. Locate the position of the image. |
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Answer» The focal length of the lens is given by `1/f=(mu-1)(1/R_1-1/R_2)` `=(1.5-1)(1/(20cm)-1/(60 cm))=1/(60cm)` or `f=60 cm a. for the image formed by lens `u=-80` cm so that `1/v=1/u+1/f` `=1/(-80cm)+1/(60cm)=1/(240cm)` or `v=240 cm` The first image `I_1` would form 240 cm to the right of the first lens. b. The second lens intercepts the converging beam as suggest by the ure. the image `I_1` acts as a virtual source of the second lens. For the image formed by this lens `u=240cm-160cm=+80` cm so that `1/v=1/u+1/f` ` =1/(80cm)+1/(60cm)=7/(240cm)` or `v=34.3cm` the fiN/Al image is formed 34.3 cm to the right of the second lens. |
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