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*Question:* An object of height cm is placed
a distance cm in front of a concave mirror of
focal length cm. What is the height, location, and
nature of the image? Suppose that the object is
moved to a new position a distance cm in front
of the mirror. What now is the height, location, and
nature of the image?

*Answer:* According to Eq. (358), the image distance is
given by

Thus, the image is *virtual* (since ), and is located cm *behind*
the mirror. According to Eq. (352), the magnification of
the image is given by

Thus, the image is *upright* (since ), and
*magnified* by a factor of . It follows that the height
of
the image is given by

If the object is moved such that cm then the
new image distance is given by

Thus, the new image is *real* (since ), and is
located 100cm *in front of* the mirror. The new magnification is
given by

Thus, the image is *inverted* (since ), and
*magnified* by a factor of . It follows that the
new height of the image
is

Note that the height is negative because the image is inverted.

** Next:** Example 13.2: Convex mirrors
** Up:** Paraxial Optics
** Previous:** Worked Examples
Richard Fitzpatrick
2007-07-14