The mirror reverses front and back, and it is with respect to this reversal that your "ring hand", say, becomes the right hand instead of the left in the image, even though the image "ring hand" remains directly opposite to your actual "ring hand", just as your head remains opposite your head, and your feet remain opposite your feet.

Nice joke, but for the record, that's an "oh", i.e. small letter 'o', for object, and stands for the distance of the object from the surface plane.

Of course if i=f we have 1/o = 1/f - 1/i = 0,

o = 1/0 = infinity

Since we are physicists, this makes perfect sense.

I read again the original post and I don't believe he was speaking of "What Portion of a Mirror is Required to View an Image? " He was speaking about the size of the image. I read him to mean that the image is half the size because the image you see is twice the distance from you to the mirror. (twice the distance is true), but the image is not half the size. That would be similar to saying that if you took two identical twins and moved one from 2 feet in front of the other back to 4 feet he would be half the size.

I agree wholeheartedly with you that you only need a mirror half the size of you to view yourself (I didn't remember it being half, but I've been in front of a mirror shaving more times than I'd care to admit and know that I don't need a six foot mirror to view my six foot height.)

There are five rules concerning images formed by planar mirrors: The image is:

virtual
upright
left-right reversed
same distance to mirror as the object is to the mirror
the exact size as the object

Also the magnification of a planar mirror is 1. M = d_i/d_o = I/O Where M = Magnification, d_i=distance from mirror to image, d_o = distance from mirror to object, I=size of Image and O=size of Object

Now what got me on this was remembering the equalities in (5) and distance properties in (4). Since we know the magnification of a planar mirror is 1 and that d_i=d_o, hence M=d_i/d_o therefore, (I)mage size MUST equal (O)bject size.

Of course rule #5 is all one needs to dispute his statement.

http://www.physicsclassroom.com/Class/refln/U13L2b.html follows below.

Lesson 2: Image Formation in Plane Mirrors

Image Characteristics

diagram As discussed in the previous section of Lesson 2, an image is a position in space where all the reflected light appears to diverge from. Since light from the object appears to diverge from this location, a person who sights along a line at this location will perceive a replica or reproduction of the actual object. In the case of plane mirrors, the image is said to be a virtual image. Virtual images are images which are formed in locations where light does not actually reach. Light does not actually pass through the location on the other side of the mirror; it only appears to an observer as though the light were coming from this position. Whenever a mirror (whether a plane mirror or otherwise) creates an image which is virtual, it will be located behind the mirror where light does not really pass. Later in this unit, we will study instances in which images are formed by curved mirrors that are real images. Such images are formed on the same side of the mirror as the object and light passes through the actual image location.

Besides the fact that plane mirror images are virtual, there are several other characteristics which are worth noting. The second characteristic has to do with the orientation of the image. diagram If you view an image of yourself in a plane mirror (perhaps a bathroom mirror), you will quickly notice that there is a left-right reversal of the image. That is, if you raise your left hand, you will notice that the image raises its right hand. If you raise your right hand, the image raises its left hand. This is termed left-right reversal. This characteristic becomes even more obvious if you wear a shirt with lettering. For example, a shirt displaying the word "NIKE" will read "EKIN" when viewed in the mirror; a shirt displaying the word "ILLINOIS" will read "SIONILLI;" and a shirt displaying the word "BOB" will read "BOB." (NOTE: Not only will the order of letters be reversed, the actual orientation of the letters themselves will be reversed as well. Of course, this is a little difficult to do when typing from a keyboard.) While there is a left-right reversal of the orientation of the image, there is no top-bottom vertical reversal. If you stand on your feet in front of a plane mirror, the image does not stand on its head. Similarly, the ceiling does not become the floor. The image is said to be upright, as opposed to inverted.

A third characteristic of plane mirror images pertains to the relationship between the object's distance to the mirror and the image's distance to the mirror. For plane mirrors, the object distance (often represented by the symbol d_o) is equal to the image distance (often represented by the symbol d_i). That is the image is the same distance behind the mirror as the object is in front of the mirror. If you stand a distance of 2 meters from a plane mirror, you must look at a location 2 meters behind the mirror in order to view your image.

A fourth and final characteristic of plane mirror images is that the dimensions of the image are the same as the dimensions of the object. If a 1.6-meter tall person stands in front of a mirror, he/she will see an image which is 1.6-meters tall. If a penny with a diameter of 18-mm is placed in front of a plane mirror, the image of the penny has a diameter of 18 mm. The ratio of the image dimensions to the object dimensions is termed the magnification. Plane mirrors produce images which have a magnification of 1.

In conclusion, plane mirrors produce images with a number of distinguishable characteristics. Images formed by plane mirrors are virtual, upright, left-right reversed, the same distance from the mirror as the object's distance, and the same size as the object.

I know what you mean, my dad is appearing in all my mirrors too.

Even weirder, when my Mom was going through the final stages of life- just drifting away, and shrinking- I noticed for the first time how some of the planes and angles of her face were reflected in mine.

We really do carry the seeds of our parents with us.

Better not play the Village People, too much psychic influence.

What you are looking at is full size, what you see an image on your retina that is about zero size, half way in between the virtual image would be half size.

I like those bathrooms with medicine cabinets on the two corner walls. When you open one a little bit and look in the other, you can stand there at the toilet and see yourself as you look to others rather than as a regular reflection. Sigh.

Two papers are better. Two papers cover the rock TWICE. That f'ing rock ain't going NOWHERE

Ahhhh!

Best 2 out of 3?