Question

A object is placed in front of a screen and a convex lens is placed at a position such that the size of the image formed is 9cm. When the lens is shifted through a distance of 20cm, the size of the image becomes 1cm. The focal length of the lens and the size of the object are respectively:. (a).7.5cm and 3.5 cm. (b).7.5cm and 4.5cm. (c).6 cm and 3cm. (d). 7.5cm and 3cm ​

Answer 1

Answer:

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