Optics and Reverse Images

This type of mirror is a concave mirror. If your face is far from the mirror, your image is inverted. If your face is close to the mirror, your face is right side up, but larger. To understand this concept one needs to study geometrical optics.

I have constructed a simple ray diagram. If the mirror is a sphere drawn by a compass, then the center of curvature is the location of the fixed point of the cumpass when the mirror's surface is drawn. The focus is the location of where light rays from infinity would all cross. It is half way between the mirror and the center of curvature. The image is the location where the CCD chip of film would be location if this mirror were in a camera.

Consider the tip of the arrow. I have drawn two rays. One moves straight to the mirror and is bent through the focus. The second hits the mirror at its center and reflects at an equal angle to the axis or center line of the drawing. The location of the intersection of these two rays is the image. If the image is below the center line, the image is inverted. If the image is above the line, the image is erect or the same as looking into a normal flat mirror.

The concept is more complicated if you are looking at the image with your eye because your eye is a lens which images the light on your retina or if you were the object in the diagram, your eye re-images the image which is close to the mirror. However, lets discuss what happens. Iif you are far from the mirror, your image is upside down and small (as in the ray diagram). If you walk towards the mirror, your image becomes larger until you reach the center of curvature. Then the image is infinitely big and dissapears to your eye. Continue to move closer to the mirror. Your image is now erect or right side up but larger. Such concave mirrors are sold for people to use to see their faces enlarged to help put make up on, etc.

Further reading can be found at Wikikpedia on optics , expecially the geometrical optics references as lenses and mirrors.

George

Thanks for the information. It was really helpful.

Just the frustration of the inability to operate my keyboard pouring out once and a while, sorry.

Maybe I should have changed it to menses and lirrors.

I am trying to cut back on the pints, don't get me wrong, I do like them and still have some but not to the point you wake up with a heavy feeling in the head and the inability to operate keyboa.......shit!

p.s. the spell checker does not pick up menses, what the heck is that word? I'll have to go and find out now.

menses

Now that is really "learning from our mistakes." And I didn't even break anything.

cr3

"YUK"

You mean you learned from my mistake, can I have at least some credit please.

Thank you for looking it up, I had forgotten about it