Mathematics and Society - OS X Lion Server

Materials Needed: straight pins,small hand mirror, cardboard or softwood to fit under paper, ruler, blockof wood for supportI Getting set up.On a piece of paper backed withcardboard draw line t, set up themirror and place the object pinabout 5 centimetres in front ofthe mirror as shown in the diagram.BLocK orWOOD toRSUPPOR.T~I HI£. Sl\ORT£.STOBJECT f DISTANCE. FROM THE=======P=II\l==-=t0BJ£.CT ToTHE:MIRROR IS T\4EOBJECT DISTAtIlCE.IISight lines.Anyone who has ever played with a toy gun knows that to sight in a target the rearsight, front sight and target must be in a straight line. We will use this samemethod to sight in the image of the pin.RE:I'LECTIOIJ OF" OBJECT PINPlace pin #1 about 2 cm in front of the mirrorand to the left of the object pin. With youreye near the table level place pin #2 so thatit is in a straight line with pin #1 and thereflection of the object pin as shown in thediagram. This is a sight line.Using the same procedure, line up two morepins along another sight line from the righthand side.III Finding the image position.Remove the mirror and its support.With a straightedge draw the linethrough pins #1 and #2. The linemust extend behind line t sincethat is where the image willappear to be found. Do the samethrough pin #3 and #4. The point of intersection is the image position.359