PHYSICS DEFINITION:
Principle of Superposition: When 2 or more waves meet
at a point, the resultant displacement is the sum of the displacements of the
individual waves.
PHYSICS KEYWORD LIST:
Diffraction: Spreading of a wave when it passes
through a gap or past the edge of an object.
Interference: Superposition of 2 or more waves from
coherent sources.
Constructive Interference: When 2 waves reinforce to
give increased amplitude at a point in space.
Destructive Interference: When 2 waves cancel to give
reduced (or zero) amplitude at a point in space.
Coherent Sources: 2 sources with exactly the same
frequency, and have 0 or constant phase difference.
Path Difference: Extra distance travelled by one of
the waves compared with the other. Path difference is often given in terms of
the wavelength of the waves.
Interference Maxima: Regions where light waves from 2
slits arrive in phase with each other; in other words, there is constructive
interference.
Coherence: Term used to describe 2 waves emitted from
2 sources that have a constant phase difference. The sources emitting such
waves are referred to as coherent sources.
Dispersion: Splitting of light into its component
wavelengths.
PHYSICS CHAPTER WISE SUMMARY:
The principle of superposition states that when 2 or more
waves meet at a point, the resultant displacement is the algebraic sum of the
displacements of the individual waves.
When waves pass through a slit, they may be diffracted so
that they spread out into the space beyond. The diffraction effect is greatest
when the wavelength of the waves is similar to the width of the gap.
Interference is the superposition of 2 or more waves from
coherent sources.
2 sources are coherent when they emit waves that have a
constant phase difference. (This can only happen if the waves have the same
frequency or wavelength.)
Path difference is the extra distance travelled by one of
the waves compared with the other.
For constructive interference, the path difference is a
whole number of wavelengths, or simply path difference.
For constructive interference, the waves are always in phase
(phase difference = 0o).
For destructive interference, the path difference is an odd
number of half wavelengths or simply path difference.
For destructive interference, the waves are completely out
of phase.
When light passes through a double slit, it is diffracted at
each slit and an interference pattern of equally spaced light and dark fringes is
observed. λ = ax/D (This equation can be used for all waves, including sound
and microwaves.
A diffraction grating diffracts light at its many slits or
lines. The diffracted light interferes with the space beyond the grating.
d Sin A = nλ
PHYSICS IMPORTANT NOTES:
Double slit: wavelength = [separation between the centres of
slit * separation between the centres of adjacent bright (or dark) fringes]/Distance
between the slits and the screen.
D sin A = nλ
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