Why Was My Answer of 63 cm for the Focal Length of a Converging Lens Incorrect?

Thread starter syllll_213
Start date Apr 15, 2025

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The focal length of a converging lens is determined using the lens formula, which relates object distance, image distance, and focal length. In this case, the object distance is 14 cm and the virtual image is located 18 cm from the object, resulting in an image distance of -4 cm (since virtual images have negative distances). Applying the lens formula (1/f = 1/do + 1/di) reveals that the correct focal length is not 63 cm. The error likely stems from miscalculating the image distance or not properly applying the lens formula. Understanding these calculations is essential for accurately determining the focal length of a lens.

Apr 15, 2025

syllll_213

Homework Statement: An object is in a distance of 14 cm from a converging lens. The lens produces a virtual image at a distance 18 cm from the object.

What is the focal length of the lens (in cm).

Relevant Equations: 1/f = 1/di + 1/do

I attempted and keyed in the answer as 63 but I was graded wrong. What am I missing?

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Apr 15, 2025

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syllll_213 said:

Homework Statement: An object is in a distance of 14 cm from a converging lens. The lens produces a virtual image at a distance 18 cm from the object.

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