Question

Medal WILL Be Given

An object is 30.0 cm to the left of a convex lens with a focal length of +8.0 cm.
Draw a ray diagram of the setup showing the location of the image [no need to, just explain to me how the convex lens would work].
Calculate the distance of the image from the lens.
Is the image upright or inverted?

Answer 1

@Garm

Do you possibly understand how to do this? :)

Answer 2

Umm if I am not mistaken in order to find image location you have to cast multiple rays from single point on an object and then see where they will re-focus back into one point.

no matter the lens you can always easily draw 2-3 rays:

Ray that passes through center of the lens will remain unaffected and continue going in straight line.

Ray cast directly straight at the lens will be bent and pass through lens focal point.

Ray cast from an object to the lens through lens focal point will be bent and exit parallel to the lens focal line.

Here is the basic representation of these three rays:
http://hyperphysics.phy-astr.gsu.edu/hbase/geoopt/imggo/cvex1.gif

Using these will not give you precise numbers but it will give you solid idea where image is located and its general shape and form. Casting rays from top and bottom of the object will easily help you to see image size and orientation.

To precisely calculate image location and size you just need two equations:

1/O + 1/I = 1/F

Where O is the object distance from lens, F is the focal strength, and I is the image distance from lens.

M = -I/O = H`/H

Where M is image magnification, I and O are image and object distances, H' is the image size, H is the object size.


This should be enough - good luck!

Answer 3

@Garm

Thank you! I had already figured all of that out on my own, but this overview is still very helpful :)