1. DIFFRACTION OF
LIGHT
Dusty West and Lee Joseph

2. Objectives
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Describe how light waves bend around
obstacles
Calculate the positions of fringes for a
diffraction grating
Describe how diffraction determines an optical
instruments ability to resolve images.

3. Introduction
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In this project we will be talking about the
diffraction of light.
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How light bends
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The position of fringes for a diffraction grating.

4. Huygens’ Principle
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Huygens stated that light waves spreading out
from a point source may be regarded as the
overlapping of tiny secondary wavelets.
That every point on any wave front may be
regarded as a new point source of secondary
waves.
This idea was known as the Huygens
Principle.

5. Huygens’ Principle
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As a wave front spreads it appears less
curved.
Very far from the original source the wave
fronts form a plane.
Example: A good example is the plane waves
that arrives from the sun.

6. Diffraction
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Any bending of a wave by means other than
reflection or refraction.
When a wave goes through an opening if the
opening is wide compared with the
wavelength, spreading is small.
Also when a slit becomes smaller compared
with the wavelength, the spreading is wide.

7. How light bends around an
object
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If you were standing on a corner of a building
and you hear someone talking but you can’t
see them.
This is because sound waves bend around a
corner because of their longer wavelengths.
Light waves can bend around corner but they
have shorter wavelengths.

8. Diffraction Grating
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Diffraction grating is used to show the colors
of white light.
When light passes through the grating it
shows the colors of white light.

9. Double Slit Experiment
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Thomas Young performed an experiment that
strongly supported the wave like nature of
light.
He reasoned that some type of interaction
would occur when two light wave met.
To test this he used a screen containing a
single narrow slit to produce a coherent light
beam.

10. Double Slit Experiment
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As a result the light diffracted and produced a
single wave front.
He re-tested this and used a new screen with
two closely spaced slits
As a result the waves combined and created a
single wave front.

11. Fringes
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Young was able to observe the effects of
interference on a screen placed at a set
distance behind the slits.
The light that is recombined by interference
produces a series of bright and dark fringes
along the length of the screen.

12. Pictures

13. Citations
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Serway, R. A., & Faughn, J. S. (2009). Holt physics.
Orlando: Holt, Rinehart and Winston.
Hewitt, P. G. (2009). Conceptual physics (10 ed.). San
Francisco: Pearson Addison Wesley.
Spring, K. R., & Davidson, M. W. (2003). Molecular Expressions
Microscopy Primer: Physics of Light and Color - Light: Particle or a
Wave?. Molecular Expressions Microscopy Primer: Physics of Light
and Color - Light: Particle or a Wave?. Retrieved October
30, 2013, from http://micro.magnet.fsu.edu/primer/lightandcolor