• involves two rays
• Specular and Diffuse
• “Law of Reflection”
LAW OF REFLECTION
When light falls on a
surface which is plane,
the angle with which the
light falls on the surface
is equal to the angle
with which the light
reflects back and the
incident ray, reflected
ray and the normal ray
lies in the same plane.
All the light travelling
in one direction and
reflecting from the
mirror is reflected in
The rays incident at
points on the
surface are reflected
Rough, dull surfaces
Specular Reflection Diffuse Reflection
An observer on the west-facing beach of a
large lake is watching the beginning of a
sunset. The water is very smooth except for
some areas with small ripples. The observer
notices that some areas of the water are blue
and some are pink. Why does the water
appear to be different colors in different areas?
The different colors arise from specular and
diffuse reflection. The smooth areas of the
water will specularly reflect the light from the
west, which is the pink light from the sunset.
The areas with small ripples will reflect the
light diffusely, so light from all parts of the sky
will be reflected into the observer’s eyes.
Because most of the sky is still blue at the
beginning of the sunset, these areas will
appear to be blue.
The light reflects off in all directions because of the
irregularities on the surface of an object that are
larger than the wavelength of light but it does not
mean that the law of reflected is flouted. All objects
obey the law of reflection on a microscopic level. This
means that at different points on the surface, the
normal is different. The angle of reflection is still
equal to the angle of incidence at that point and the
normal is unique at that point in the surface.
NAIVE CONCEPTION (corrected
Keep in mind that the diagrams are made to view
in a microscopic outlook of an object on the atomic
level. There are billions of light rays and billions of
surfaces. So while seeing things, a lot of the light is
diffused. That's why when a person looks at
something, even if it is not directly faced into the
sun, the person still get enough light to see it.
NAIVE CONCEPTION (corrected
In diffused reflection light scatters away then
people must not be able to see it. So, how are
people seeing any things in the world?
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