Lenses- magnification adn focal length

In summary, this person is trying to find out how magnification and focal length relate to each other. They did an experiment to measure the magnification of lenses at different distances from the lens, and also calculated the focal length. They are now stuck on how to write all of this up and what graphs to draw. If you are able to help them out, please do!
  • #1
PhysicsChick8
5
0

Homework Statement


Hey,,
I was wondering if anyone could help me with some physics work i am doing as i am completely stuck.
Is there supposed to be any relationship with the magnification and focal length of lenses and if so what is it?
I did an experiment and measure the magnification of lenses different distances from the lenses and also calculated the focal length at these points. Now i am stuck on how to write all this up and what graphs to draw.
Any help would be much appreciated :s
xxx


Homework Equations



I used 1/v-1/u=1/f for focal length
and size of image/ size of object for magnification

The Attempt at a Solution

 
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  • #2
Welcome to PF!

Hi PhysicsChick8! Welcome to PF! :smile:

See the PF Library entry on lens :wink:​
 
  • #3
thanks i read that but I'm kinda very bad at physics and need it explained in very simple terms if possible without too many confusing equations xx
 
  • #4
As the Library says …

The image is magnified (with respect to the size of the object) by the factor m = -di/do

and …

do is positive for a real object and negative for a virtual object (See Images section).
di is positive for a real image and negative for a virtual image (See Images section).

and …

For the common situation where the object and image are real (do and di both positive), the magnification is negative indicating an inverted image with respect to the object.
 
  • #5
so if i were plotting stuff on a graph what would i plot? x
 
  • #6
Well, what are you trying to show? :smile:
 
  • #7
thats the problem i don't know,,, we had to choose an experiment and i choose the magnification and power of lenses as it seemed easy. Now i have to write it up and draw graphs but I am not sure what of as i don't really know what is linked. I really am useless at this if you haven't guessed already x
 
  • #8
I suppose the obvious graphs would be di against do, and m (= -di/do) against do.

Try drawing them, and see what you get. :smile:
 
  • #9
thank you :D x
 

1. What is the difference between magnification and focal length?

Magnification refers to the ability of a lens to make an object appear larger or smaller. It is measured by the ratio of the size of the image produced by the lens to the size of the object. Focal length, on the other hand, is the distance between the lens and the point where light rays converge to form a sharp image. It determines the angle of view and the size of the image produced by the lens.

2. How does the magnification of a lens affect the size of the image?

The higher the magnification, the larger the image produced by the lens. This means that objects will appear larger and closer when viewed through a lens with a higher magnification.

3. Can the focal length of a lens be changed?

Yes, the focal length of a lens can be changed by adjusting the distance between the lens and the image sensor or film. This is known as changing the lens's focus. Some lenses also have the ability to physically change their focal length, such as zoom lenses.

4. How does the focal length of a lens affect the field of view?

The focal length of a lens determines the angle of view, which is the amount of the scene that the lens can capture. A shorter focal length results in a wider angle of view, allowing the lens to capture more of the scene. A longer focal length, on the other hand, results in a narrower angle of view, making the lens capture a smaller portion of the scene.

5. What is the relationship between focal length and depth of field?

The focal length of a lens also affects the depth of field, which is the range of distance that appears in focus in an image. A shorter focal length results in a larger depth of field, meaning that more of the scene will appear in focus. A longer focal length, on the other hand, results in a shallower depth of field, with only a small portion of the scene appearing in focus.

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