INTERFERENCE
Prasanth P
Government Engineering College,Thrissur
January 21, 2021
,INTRODUCTION
I The best evidence for the wave nature of light is interference
phenomenon. Due to interference, we will observe many
observations in our day today life, such as multiple colours on
soap bubbles as well as on oil film when viewed under sun
light.
I This was experimentally demonstrated by Thomas Young,
through double slit experiment.
I Interference concept is explained on the basis of superposition
of wave’s.
I When two light waves superimpose, then the resultant
amplitude or intensity in the region of superposition is
different from the amplitude of individual waves.
,Definition
I When light from two coherent sources superimpose each other
a redistribution of intensity in the region of superposition
takes place which is known as interference.
I Based on the interference pattern observed there are two
types of interference.
I Constructive interference The path difference between the two
waves is equal to the integral multiple of wave length(λ) the
constructive interference occurs.
pathdifference = nλ
Where n = 0, 1, 2, 3, 4 . . .
I Destructive interference The path difference between the two
waves is equal to the odd integral multiple of ( λ2 ) destructive
interference occurs.
(2n + 1)λ
pathdifference =
2
Where n = 0, 1, 2, 3, 4 . . .
, The optical path
I Consider a light wave traveling through a medium of
refractive index µ and length d with a velocity v. Then µd is
the optical path traveled by the light.
I ie, a distance d in a medium of refractive index µ is equivalent
to a distance µd in air.
Prasanth P
Government Engineering College,Thrissur
January 21, 2021
,INTRODUCTION
I The best evidence for the wave nature of light is interference
phenomenon. Due to interference, we will observe many
observations in our day today life, such as multiple colours on
soap bubbles as well as on oil film when viewed under sun
light.
I This was experimentally demonstrated by Thomas Young,
through double slit experiment.
I Interference concept is explained on the basis of superposition
of wave’s.
I When two light waves superimpose, then the resultant
amplitude or intensity in the region of superposition is
different from the amplitude of individual waves.
,Definition
I When light from two coherent sources superimpose each other
a redistribution of intensity in the region of superposition
takes place which is known as interference.
I Based on the interference pattern observed there are two
types of interference.
I Constructive interference The path difference between the two
waves is equal to the integral multiple of wave length(λ) the
constructive interference occurs.
pathdifference = nλ
Where n = 0, 1, 2, 3, 4 . . .
I Destructive interference The path difference between the two
waves is equal to the odd integral multiple of ( λ2 ) destructive
interference occurs.
(2n + 1)λ
pathdifference =
2
Where n = 0, 1, 2, 3, 4 . . .
, The optical path
I Consider a light wave traveling through a medium of
refractive index µ and length d with a velocity v. Then µd is
the optical path traveled by the light.
I ie, a distance d in a medium of refractive index µ is equivalent
to a distance µd in air.
