2. Objective 15.1
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Describe how light waves bend around
obstacles and produce bright and dark
fringes.
Identify the conditions required for
interference to occur.
3. Lesson Objectives- Paraphrased
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We will be describing the interference of light
We will also be identifying the conditions
required for interference to occur
4. So what is interference of light?
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Light passing through the specimen is
scattered and diffracted into divergent waves
by tiny details and features present in the
specimen
5. Principle of Superposition
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the principle of superposition states when
two waves interfere, the resulting amplitude
of the medium at any location is the
algebraic sum of the amplitude of the
individual waves at that same location.
6. Constructive Interference
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A type of interference that occurs along the
medium when two interfering waves have a
displacement going in the same direction
As a result the amplitude is
increased, resulting in a bright color
The higher and higher amplitude gets the
brighter and brighter the color gets, vice
versa.
7. Destructive Interference
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two moving waves that meet along the
medium in opposite directions and interfere
as a result the amplitude is decreased
this results in a dark or dim spot in the light
wave
8. History of light interference
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Thomas Young was the first to demonstrate
interference of light in 1801.
Young discovered that when light of a single
color was directed through two closely
spaced pinholes fringes of brightness and
darkness were produced on the screen
behind.
9. Where do the bright colors come
from?
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two crests (or troughs) come
together, amplitude becomes an additive
this results in constructive interference
the product of both wavelengths is a bright
color (s)
10. Where do the dim colors come
from?
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destructive interference is from crest and
troughs being out of sync
the light either cancels out or produces dim
spots
11. Diffraction
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it is the bending of waves around an object
accompanied by an interference pattern
Huygen's principle applies diffraction and
light interference together
12. Huygen's Principle
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this principle states that every point on a
wave front is a source of wavelets, light will
be spread out when it passes through a slit
13.
14. Double Slit Experiment materials
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light source- any source of your choice
thin sheet- make sure it has two vertical slits
in it
detection sheet- could be cardboard or wood
