PURPOSE: To show the nature of a virtual image.
DESCRIPTION: This is a large-scale demonstration of a virtual image created by a plane mirror. The object and image are lab stands positioned at equal distances in front of and behind the mirror.
With only the object stand in place, long strings tied to nails at the top of the mirror are aligned by students so that they appear to be coming from the image. All strings properly aligned will converge on the image position. Additional string from each nail behind the mirror can then be raised to show that they converge at a point behind the mirror.
The image stand is then placed at the point where the strings converge. The top of this image shows no parallax when the entire mirror apparatus is rotated.
REFERENCES: (PIRA unknown.) See Demonstration Reference File for paper describing this demonstration.
EQUIPMENT: Mirror with strings, object and image stands, on rotating platform.
SETUP TIME: 5 min.
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