INTERFERENCE
Real Life Example of INTERFERENCE
Applications of Interference
1. Optical Testing: Generally, interference is used in testing surface qualities like:
flat surface, spherical surface, roughness of surface etc.
2. Space applications -Radio Astronomy, Measuring light intensity, in retrieving images
from the telescopes.
3. Determine the refractive index of an unknown transparent liquid
4. To determine the wavelength of an unknown light source
5. Calculate the thickness of a mica sheet
6. 3-D imaging: Holography
,Theories of Light
In the seventeenth century two rival theories of the nature of light were proposed:
The wave theory
The corpuscular theory
Wave Theory
The Dutch astronomer Huygens (1629-1695) proposed a wave theory of light. He
believed that light was a longitudinal wave, and that this wave was propagated through a
hypothetical medium called the 'ether'.
Corpuscular Theory
In 1690 Newton proposed the corpuscular theory of light. He believed that light is
emitted out from a source in form small particles, and this view was accepted for over a
hundred years.
Quantum Theory
The quantum theory put forward by Max Planck in 1900 combined the wave theory and
the particle theory, and showed that light can sometimes behave like a particle and
sometimes like a wave. It is a form of energy packet ‘quanta=hν’
, Modem theories- Electromagnetic Theory
Twentieth-century ideas have led us to believe that light is:
(a) a transverse electromagnetic wave with a small wavelength, and
(b) emitted in quanta or packets of radiation of about 10 -8 s duration with abrupt phase
changes between successive pulses.
Wave theory Corpuscular theory
Reflection Reflection
Refraction Photoelectric effect
Diffraction
Interference
Definition of waves
Waves are periodic disturbances which propagate (move) through a medium. Waves can
be viewed as transfer energy rather than the movement of a particle
Characteristics of Waves
Amplitude: The maximum displacement from the mean position
Wavelength: The distance travelled by the wave between two consecutive crest or
trough. Also can be defined as the distance covered in one complete oscillation.
Time Period: The time take by the wave to complete one oscillation
Frequency: Number of waves passing by a specific point per second
Phase: of a point in a wave is the fraction of oscillation from an initial chosen point.
One complete cycle one wavelength is equal to phase change of 2π radian
y
ωt
a
Real Life Example of INTERFERENCE
Applications of Interference
1. Optical Testing: Generally, interference is used in testing surface qualities like:
flat surface, spherical surface, roughness of surface etc.
2. Space applications -Radio Astronomy, Measuring light intensity, in retrieving images
from the telescopes.
3. Determine the refractive index of an unknown transparent liquid
4. To determine the wavelength of an unknown light source
5. Calculate the thickness of a mica sheet
6. 3-D imaging: Holography
,Theories of Light
In the seventeenth century two rival theories of the nature of light were proposed:
The wave theory
The corpuscular theory
Wave Theory
The Dutch astronomer Huygens (1629-1695) proposed a wave theory of light. He
believed that light was a longitudinal wave, and that this wave was propagated through a
hypothetical medium called the 'ether'.
Corpuscular Theory
In 1690 Newton proposed the corpuscular theory of light. He believed that light is
emitted out from a source in form small particles, and this view was accepted for over a
hundred years.
Quantum Theory
The quantum theory put forward by Max Planck in 1900 combined the wave theory and
the particle theory, and showed that light can sometimes behave like a particle and
sometimes like a wave. It is a form of energy packet ‘quanta=hν’
, Modem theories- Electromagnetic Theory
Twentieth-century ideas have led us to believe that light is:
(a) a transverse electromagnetic wave with a small wavelength, and
(b) emitted in quanta or packets of radiation of about 10 -8 s duration with abrupt phase
changes between successive pulses.
Wave theory Corpuscular theory
Reflection Reflection
Refraction Photoelectric effect
Diffraction
Interference
Definition of waves
Waves are periodic disturbances which propagate (move) through a medium. Waves can
be viewed as transfer energy rather than the movement of a particle
Characteristics of Waves
Amplitude: The maximum displacement from the mean position
Wavelength: The distance travelled by the wave between two consecutive crest or
trough. Also can be defined as the distance covered in one complete oscillation.
Time Period: The time take by the wave to complete one oscillation
Frequency: Number of waves passing by a specific point per second
Phase: of a point in a wave is the fraction of oscillation from an initial chosen point.
One complete cycle one wavelength is equal to phase change of 2π radian
y
ωt
a
