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Scattering and Diffraction
Name: sriram
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 2000-2001
Question:
what is the difference between scattering and diffraction
since in both cases waves bend at the point of contact with the object?
Replies:
Sriram,
Scattering and diffraction are both things that waves can experience, but
they are not the same thing. They are not caused by the same thing.
Scattering is understood in terms of particles, and behaves similarly for
waves. We do not truly understand why diffraction occurs.
Scattering is effectively bouncing off something. For waves, it is being
absorbed and then almost immediately released in another direction.
Scattering occurs because an object gets in the way of the wave. The part
of the wave that strikes the object must either pass through (light through
glass), be absorbed (sunburn), or be scattered (light bouncing off the wall,
so we can see the wall).
Diffraction is due to part of a wave being removed. It is an action taken
by the part of the wave that does NOT strike an object. Imagine a straight
wave traveling forward along the surface of the water. If you block the
left half of the wave, the right half will not just keep moving forward. It
will expand toward the left, toward where the blocked wave would have been.
A wave seems to continuously regenerate itself, always pushing forward on
itself. When a section is removed, parts of the wave get pushed in to the
empty spot. It in some ways correlates to your pushing a wide row of
blocks. If many people push on a few blocks each, a straight line can be
maintained. If one person tries to do so, the blocks in front will tend to
spread out. This is the best description of diffraction I know.
Dr. Ken Mellendorf
Illinois Central College
Hello,
In a sense both refer to light being re-directed as a result of interacting
with atoms. However, a more precise definition used in optics distinguishes
these two. Scattering generally implies interaction of waves (or photons)
with spatially uncoordinated (unordered) atoms. This means that if one looks
at a picture of the scattered radiation, one would see a spatially
continuous footprint. Diffraction, on the other hand, occurs when the object
or part of the object is made up of ordered atoms. These atoms, being neatly
arranged, "scatter" the waves or photons in a coordinated way (i.e., in
specific direction(s)) giving rise to what we can see on a film as bright
spots rather.
AK
Ali Khounsary, Ph.D.
Advanced Photon Source
Argonne National Laboratory
Light scatters off of particles and surfaces. Diffraction is a special type
of scattering that leads to large scale interference effects. Usually this
is because the surface causing the scattering has some overall organization,
such as a ruled diffraction grating or the knife edge of a slit.
Greg Bradburn
Light scatters off of particles and surfaces. Diffraction is a special type
of scattering that leads to large scale interference effects. Usually this
is because the surface causing the scattering has some overall organization,
such as a ruled diffraction grating or the knife edge of a slit.
Greg Bradburn
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Update: June 2012
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