Q57 of 123 Page 412

A convex lens produces a double size real image when an object is place at a distance of 18 cm from it. Where should the object be place to produce a triple size real image?

the distance between object and the lens, u = 18cm

The magnification of the real image is given as m= -2





Now, using lens maker’s formula,





Now, the required magnification m=-3 =v/u


Again,





Hence, the object should be placed 16 cm from lens


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