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Focal length of concave lens shown in figure is 60 cm. Find image position and its magnification. |
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Answer» Solution :For the given situation, `u=-30cm, f=-60cm` USING the LENS formula, we have `1/v-1/-30=1/-60` SOLVING this equation, we get `v=-20cm` Further, `m=v/u=(-20)/(-30)=+(2)/(3)`. POINT b is `2mm` above the principal axis. Therefore, its image b' will be `(2)((2)/(3))` or `4/3mm`, above the principal axis. Similarly, point a is 1mm below the principal axis. therefore, its image a' will be `(1)((2)/(3))` or `2/3mm` below the principal axis. The FINAL image is as shown in fig. `31.67` 
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