Formation of Images by lenses

In summary, the new image distance is approximately -883.5 cm. This indicates that the final image is virtual and located to the left of the lens. It is important to keep all digits in calculations to get a more accurate result.
  • #1
lenaosu
2
0
1. An object is placed in front of a converging lens in such a position that the lens (f = 11.0 cm) creates a real image located 27.0 cm from the lens. Then, with the object remaining in place, the lens is replaced with another converging lens (f = 19.0 cm). A new, real image is formed. What is the image distance of this new image?


2. I tried using 1/f= 1/d0-1/di to solve for this. But it doesn't seem to be working.
Any suggestions.
 
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  • #2
Hi lenaosu,

The thin lens formula is

[tex]
\frac{1}{f}=\frac{1}{d_o}+\frac{1}{d_i}
[/tex]

Depending on the problem, any of these variables might turn out to be negative numbers. What numbers are you using, and what do you get?
 
  • #3
i used the thin lens equations twice.
1.) 1/f-1/di=1/do
1/11-1/27=1/di
di=18.6cm

2.) 1/f-1/do=1/di
1/19-1/18.6=1/di
di= -883.5cm

My calculations for my second image doesn't seem correct. My image should be to the left of my lens and not to the righ tof my lens.
 
  • #4
Since the object distance is less than the focal length for the second lens, it's image should be virtual, and so I think the fact that the final image length is negative is right.

However, you should not round your result from step 1 to three digits. Keep all the digits you can, and then round the final answer. Here it makes a relatively large difference.
 

1. How do lenses form images?

Lenses form images by refracting light, which means they bend light rays as they pass through the lens. This bending of light causes the light rays to converge or diverge, resulting in an image being formed.

2. What is the difference between convex and concave lenses?

Convex lenses are thicker in the middle and thinner at the edges, and they converge light rays to form real images. Concave lenses are thinner in the middle and thicker at the edges, and they diverge light rays to form virtual images.

3. How does the focal length of a lens affect the image formed?

The focal length of a lens is the distance between the lens and the point where it forms a clear image of an object placed at infinity. A shorter focal length means the lens will have a wider field of view and produce a larger image. A longer focal length means the lens will have a narrower field of view and produce a smaller image.

4. Can lenses form images of objects at different distances?

Yes, lenses can form images of objects at different distances. This is because lenses have the ability to change their focal length by adjusting the distance between the lens and the object. This is known as accommodation and allows us to focus on objects at different distances.

5. Why do images appear upside down when viewed through a lens?

Images appear upside down when viewed through a lens because of the way light rays are bent as they pass through the lens. This phenomenon is known as refraction, and it causes the top and bottom of an image to switch places, resulting in an inverted image.

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