Solving a Focal Length Puzzle: Find the Image Location and Size

In summary, a converging lens with a focal length of 25cm creates an image located at -37.5cm and with a size of 2.50cm when a 1.00cm tall object is placed 15.0cm in front of the lens. However, the ray diagram does not show the image at 37.5cm behind the lens, which may be due to not understanding the sign conventions. This issue has been discussed in another post.
  • #1
lilkrazyrae
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A converging lens has a focal length of 25cm. A 1.00cm tall object is placed 15.0cm in front of the lens. Find the image location and size, and describe it. Draw a ray diagram.

Ok so I get 1/p + 1/q = 1/f rearranged for q=pf/p-f which equals -37.5, so the object is 37.5cm behind the lens. and then m=-q/p=2.50cm. The h'=mh(i)=2.50*1.00=2.50cm tall. This all works out

BUT the ray diagram doesn't make the image at 37.5cm behind the lens. Some one help please!
 
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  • #2
Did you learned the sign conventions? what is the sign of the object distance?
 

FAQ: Solving a Focal Length Puzzle: Find the Image Location and Size

1. How do you determine the focal length of a lens?

The focal length of a lens can be determined by measuring the distance between the lens and the image plane when the object is in focus. This distance is the focal length.

2. What is the relationship between focal length and image size?

The focal length of a lens is directly proportional to the size of the image. This means that as the focal length increases, the size of the image also increases.

3. What is the equation for calculating image location and size?

The equation for calculating image location and size is: 1/f = 1/d0 + 1/di, where f is the focal length, d0 is the object distance, and di is the image distance.

4. How do you solve a focal length puzzle?

To solve a focal length puzzle, you need to know the object distance, image distance, and the magnification of the image. Using these values and the equation 1/f = 1/d0 + 1/di, you can calculate the focal length of the lens.

5. What factors can affect the accuracy of solving a focal length puzzle?

Some factors that can affect the accuracy of solving a focal length puzzle include errors in measuring the object and image distances, variation in the magnification of the image, and lens distortion. It is important to take multiple measurements and make adjustments for any known errors to improve accuracy.

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