Prince Ganai Light
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PRINCE AHMAD GANAI Nature of Light Department of Physics-National Institute of Technology Srinaga
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The lecture was given by P.A Ganai to +2 teachers on their 3rd Refresher course held at SIE.
Transcript of Prince Ganai Light
PRINCE AHMAD GANAI
Nature of Light
Department of Physics-National Institute of Technology Srinagar
What is light. Vision and comprehension of light. Illusions. Physics of Light. Newton and Huygen. Youngs experiment Maxwells EM- theory Quantum theory of light Research still in progress
LIGHT:
Light can confuse you
Physics of Light
How does it behave? Reflection Refraction Dispersion What models can we use to: understand light predict other behaviour How can we apply our knowledge to do something useful: microscopes, telescopes, . . .
Optics
Ray theory of light
Dispersion
Light as wave
The Wave Nature of Light
Interference : Thomas Young (1803):
Light as wave
Interference
Diffraction
Light: Particles or Waves? In 1700s the particle model of light
was assumed By 1830, the wave theory was
generally accepted By 1900, light was known to be an
electromagnetic wave
Electromagnetic Theory of Light
Maxwell’s Equations
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EM- wave equation
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EM-Spectrum:
EM- THEORY
• First successful theory of unification.• Electricity, Magnetism, and Light• Origin of Light- explained.• Microscopic explanation to reflection and ref.• Radio wave production and transmission.• But wait------- Next century will hit you
Light is still a problem
Two mega theories are born ,because we want to answer the basic question, What is light?
1. Special theory of relativity.2. Quantum Mechanics.
Relativity
Theory was perceived for invariance requirements of Maxwell’s equations.
Constancy of light becomes basic postulate of the first mega theory of 20th century.
Experiments verified the theory and the concept of space and time changes for ever.
Quantum Physics
•Origin of light challenged.•How can atom be stable.•New rules required.•Wave concept in trouble.• No explanation to-
1. Photo electric effect.2. Compton effect3. Pair production
The Photoelectric Effect
Compton Scattering
Pair production.
Light and matter are different manifestations of same thing.
Quantum theory of Light
Double slit experiment
Quantum theory of light
•Light is both wave and particle•Observer decides the choice.
•Giving light yet another new twistE. Plum, J. Zhou, J. Dong, V. A. Fedotov, T. Koschny, C. M. Soukoulis, and N. I.
Zheludev
Phys. Rev. B 79, 035407 (2009) – Published January 12, 2009
CURRENT RESEARCH
Future applications.
Thankx
