1. Place a piece of cardboard on the table in front of you. Place a piece of white paper over the cardboard. Stand a mirror, long edge down, at the center of the paper. Hold in place with a block of wood. Draw a line behind the mirror to show where the mirror is located in case it is moved accidentally.

2. In front of the mirror draw a triangle (blue lines) and label corners of the triangle ABC. Place an observation pin at point X at left and Y at right. Place a pin at A on the triangle.

3. {It is important that you get your face at the level of the tabletop when looking into the mirror.}

Looking over the top of pin X, look into the mirror at the image of pin A. Carefully place pin R (as close as possible) at the mirror so that pins X, R, and the image of A line up. Remove mirror. Draw lines AR & RX.. Extend RX behind the mirror as a dashed line.

Light is traveling along path AR & RX to reach your eye. Because your brain knows that light travels in straight lines, your eye is fooled into believing that light is coming from a pin located along the red dashed line. But where on the dashed line? Remove pin R.

4. Repeat steps 2 & 3, this time from the right-hand observation point Y. Now draw AR' & R'Y. Extend as a dotted line R'Y until it intersects with the extension of XR. The point of intersection represents the perceived location of the virtual image of pin A.

5.Repeat stps 2-4 for pins located at the other vertices of the blue triangle.

6. How well did you do?
a) Draw a line from Object Point A to Image Point A'. The line drawn in step 1 to represent the reflecing surface should be perpendicular to this connecting line and should bisect it. ditto B-B' and C-C'.
b) Fold the paper on the line representing the reflecting surface (from step 1). The
blue triangle ABC should be congruent to the image triangle A'B'C' and should cover it.

last edited 03/16//08