Calculating Magnification with lens, an object, and a screen.

In summary, a lens with a focal length of 9 cm forms an image of an object placed 3.7 times the focal length to the left of the lens. The distance between the object and image is fixed. When the lens is moved towards the screen, the object and image distances are switched, resulting in a new object distance equal to the previous image distance. This results in a new image being formed, with a magnification equal to the initial case. The distance between the object and image remains constant.
  • #1
jmacmartin
4
0

Homework Statement



A lens with focal length fo = 9 cm forms an image of an object placed a distance d=3.7fo to the left of the lens, onto a screen to the right of the lens. The distance L from object to image is fixed. The lens is now moved toward the screen a distance x until an image is formed again. (a) What is the magnification in the initial case? (b) How far was the lens moved? (c) What is the magnification in the second case? (d) What is the distance L between the object and the image?

Homework Equations



1/f = 1/s + 1/s'

and

m = -(s/s')

The Attempt at a Solution



I just figured out part A and am now stuck on part B. I'm not sure how to go about solving it. I read online that "when the lens is moved, the object and image distances are switched." Can someone please explain to me why this is? I can't seem to find any information in my book. Not looking for the answer, but more how to understand what happens as this lens is moved.

Thanks!
 
Last edited:
Physics news on Phys.org
  • #2
It comes from the thin lens equation:

1/f = 1/s + 1/s'

You can switch the object and image distances and the equation still holds.
So moving the lens until the image distance is equal to the previous object
distance will result in a new object distance equal to the previous image distance.
 

What is magnification and why is it important?

Magnification is the ratio of the size of an image to the size of the original object. It is important because it allows us to see objects in greater detail and helps us to study and understand the world around us.

What is the formula for calculating magnification?

The formula for calculating magnification is: Magnification = Size of image / Size of object

Can magnification be greater than 1?

Yes, magnification can be greater than 1. This indicates that the image is larger than the original object.

What is the role of the lens in calculating magnification?

The lens is a crucial component in calculating magnification. It helps to focus and enlarge the image of the object onto the screen, making it easier to measure and calculate the magnification.

How do you use a lens, object, and screen to calculate magnification?

To calculate magnification, place the object in front of the lens and adjust the distance between the lens and the object until a clear and focused image is seen on the screen. Measure the size of the image and the size of the object, then use the formula: Magnification = Size of image / Size of object to calculate the magnification.

Similar threads

  • Introductory Physics Homework Help
Replies
3
Views
339
  • Introductory Physics Homework Help
Replies
19
Views
477
  • Introductory Physics Homework Help
Replies
3
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
917
  • Introductory Physics Homework Help
Replies
12
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
10
Views
1K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
Replies
2
Views
615
  • Introductory Physics Homework Help
Replies
3
Views
808
Back
Top