Convex Lens Problem: Find Focal Length

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To find the focal length of a convex lens when an object is 90 cm from a screen and the image is formed at two locations separated by 30 cm, one must apply the lens formula and the concept of image formation. The discussion emphasizes that simply posting a question without effort is not conducive to receiving help. Participants are encouraged to use a structured approach and provide their work for better assistance. The focal length can be calculated using the distances provided, but engagement with the problem is necessary for effective learning. Properly framing questions and showing effort is essential in educational forums.
Siddharth Venu
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A screen is placed 90cm from a object. The image of the object on the screen is formed by a convex lens at
two different locations separated by 30cm. The focal length of the lens is what?
 
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