If you know where the mirror and object are, you can always determine where the image is.
The image will always be as far behind the mirror as the object is in front of it.
The image and object will always be directly behind the mirror from the object. i.e. a line drawn from the object to the mirror always passes directly through the plane of the mirror.
Example: Locating Images
Indicate the images of the following points (where they exist).
Dhas no image. D is behind the mirror.
C is one square in front of the mirror and so its image, C’, will appear one square behind the mirror.
B is three squares in front of the mirror and so its image, B’, will appear three squares behind the mirror.
A is one square in front of the mirror and so its image, A’, will appear one square behind the mirror.
Whilst A is not directly in front of the mirror, there will still be an image of A. Any point which is front of the plane of the mirror (reflecting surface) will have an image.
Not all images can be seen simultaneously. Which images can actually be seen will depend on where the observer is standing.
Example
In the following diagram, the location of the object O and its image I are known. Use this information to accurately construct and label the location of the mirror M.
a line is drawn between O and I.
the mirror must lie halfway between O and I.
the mirror must be perpendicular to the line
such that I lies directly behind O.
Note:
Care is taken to ensure the mirror is drawn with the front (reflective surface) facing the object.
