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Nature and reflection of light
the fact that no light comes from that spot. The 2. The image is upright.
position of the image can be determined by If you stand in front of a plane
drawing and extending the reflected rays behind mirror, your image appears
the mirror until they intersect, as shown in Figure upright; that is, the image of
4.16. In other words, the image seems to be the your head appear at the top
point from which all the reflected rays emerge. and that of your feet at the
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Moreover, the incident ray, reflected ray, and the bottom. This is because plane
normal all lie in the same plane. mirrors form upright images,
not inverted images.
3. The image is the same size as
Mirror
Reflected ray the object.
The image of an object placed
Incident ray in front of a plane mirror is
the same size as the object.
Object Image The ratio of the image size
to the object size is called
magnification. Plane mirrors
Incident ray
produce images which have a
magnification of 1.
Reflected ray
4. The image is the same distance
behind the mirror as the object
Figure 4.16: Image formation by a plane mirror is in front of the mirror.
If you stand a distance of three
Characteristics of images formed in a plane metres from the plane mirror
mirror you must focus at a location
A plane mirror is a simple glass with a flat three metres behind the mirror
surface. The only difference from other types to view your image.
of glass is that its back has been silvered. The 5. The image has a left-right
image formed by a plane mirror has several reversal.
characteristics. These include the following: If you view your image in a
1. The image formed is virtual (not real). plane mirror, you will notice
When an object is placed in front of the that it appears to be laterally
plane mirror, its image will appear to be in inverted. This means that
a position behind the mirror. This image is when, for example, you
raise your left hand, the
said to be virtual, that is not real, since it is image appears to indicate a
in a location where the light does not reach, raised right hand. If you are
even though it appears like it does. It only wearing a shirt with lettering,
appears to the observer as though the light for example, WAY, it would
is coming from this point. appear as YAW. Note that
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