physics lens 問題..thx

Question

image refracted by convex lens is inverted ,(when the image distance is greater than the focal length , i.e.real image) , and may be magnified/diminished/as the same size of objects.

1a)besides inverted(this i can understand from the diagram),why is it also laterally inverted?
1b)why did people who wear convex lenses can see images that are erect?
2)will people who wear concave lenses see images that are diminished?

Answer 1

1a. First, you draw a ray diagram of an object and its inverted image on a piece of paper.

Now hold the paper horizontally, you can see that the object and the image are on opposite sides of the principal axis (i.e. if the object is on the left side, then the image is on the right side), the image has been laterally inverted.

1b. For a distance object, if you view it behind a convex lens at a distance greater than its focal length, the image is inverted.
However, should you view at behind the lens at a distance shorter than the focal length, the image is erected. You can visulaize this effect by drawing a ray diagram, as the rays are still above the principal axis when they are [caught] by your eyes.

Since eye glasses are usually worn close to the eyes, the distance between the lens and the eyes is longer than the focal length of the lens worn, thus an erect image is seen.

2. Yes, concave lens diverges light rays. The image so formed must be smaller than the size of the object.