History of Light history of light history .pdf

The history of light spans millennia of scientific inquiry and technological advancement. Early civilizations observed and utilized natural light sources like the sun and fire for warmth, illumination, and as markers of time. Ancient Greeks, including Aristotle and Euclid, theorized about light's nature and behavior, proposing ideas that influenced later thinkers.

In the Middle Ages, Islamic scholars such as Ibn al-Haytham conducted groundbreaking experiments on optics, refining theories about how light travels and interacts with objects. Their work laid the foundation for the scientific method in studying light.

The Renaissance saw renewed interest in optics, with scientists like Kepler and Galileo making significant contributions to understanding how lenses and mirrors could manipulate light. This era also marked the development of the first practical devices such as eyeglasses and telescopes.

The 17th and 18th centuries brought crucial advancements, including Newton's experiments with prisms and the discovery that white light is composed of a spectrum of colors. This laid the groundwork for understanding light as both a particle and a wave.

The 19th century saw rapid progress with the development of wave theory by scientists like Young and Fresnel, which explained phenomena like interference and diffraction. Maxwell's equations unified electricity and magnetism, paving the way for the understanding of light as an electromagnetic wave.

In the early 20th century, Einstein's work on the photoelectric effect introduced the concept of photons, particles of light. Quantum mechanics further revolutionized our understanding of light's behavior at the atomic and subatomic levels.

Modern developments continue to expand our understanding and applications of light, from lasers and fiber optics to quantum optics and photovoltaics. Today, light not only illuminates our world but drives technologies in communication, medicine, and beyond, shaping the future of science and society.

1. Euclid (320-275 BC)
•Geometry
•36 Theorems on the vision

2. Euclid (320-275 BC)
•Rays are emitted from eyes
•More rays more clear vision
•Vision dependent upon distance

3. Ptolemy (100-170 AD)
(astronomer, mathematician, Music Theorist and
geographer)
•Same as Euclid
•Provided laws of reflection and
refractionin His Book

4. Intromission Theory By Aristotle
•Light Comes from outside
but no experimental
Evidence.

5. Ibnal Haytham(Alhazen) (965-1040)
(انبمثيهلا)
•Father of Optics
•Studied the structure of eye.
•Proved Euclid & Ptolemy wrong.
•1
st
time gave Reflection and Rarefaction Laws
•(Book of Optics (رظانملا باتك

6. ISAAC NEWTON (1643-1727)
•Laws of Motion (which still bore Students)
•Law of Gravitation
•Optics and much more in PHYSICS
•Developed CALCULUS
•Method to find roots of equations and much more in MATHS
•Two Books PRINCIPIA & OPTIKS

7. HUYGEN(1629-1695)
•Home Studies Till the age of 16 years.
•Made Expression for the CENTRIPETAL FOCE in
1659.
•Discover the RINGS OF SATURN and its moon TITAN.
•Invented PENDOLUM CLOCK in 1657 which remain in
use for about 300 years.

8. NEWTON &HUYGENS
(LIGHT THEORY)
•Huygens provided Wave Theory that admits light is a
wave.
(Published in TREATISE in 1690)
•Newton provided Corpuscles Theory that admits light
is made of tiny particlescalled Corpuscles.
(Published in OPTIKS in 1704)
ےھت لاب ےبمل ےک ںونود-

9. Side INFORMATION
ےک ںونود لابےھت یھب ےلایرگنھگ-

10. HUYGENS
Justifications
•Light crosses each other without deflection.
•Formulated Reflection and Rarefaction Laws
•Provided Huygens Principles
•Explain double refraction by Iceland Spar Crystal
•Said Light passes through a medium called Aether.
تاب رھںیھنیتاج ینام-

11. NEWTON
Justifications
•Admitted the Corpuscular are weightless, travel with high speed.
•Different colors are due to different sizes of corpusculars.
•Formulated Reflection and Rarefaction Laws

12. One Was The Main Difference
•Both prepared the laws of reflection but……
•When the light passes from air to another medium, it bends
toward normal why?????
•Newton: Molecules attracts the light (gravity). Speed is morein
medium than air.
•Huygens: Speed is lessin medium.
اڑگھج اک راکیب- ںیھن یھ ڈیپس تقو سا ںیم اوھ
یھت مولعم-

13. Francesco Maria Grimaldi(1618-1663)
•While working with Riccioli, discussed free
falling objects.
•Proved Galileowrong “Objects reach at same
time on the ground”.
•Fell lead and wood balls

14. Francesco Maria Grimaldi(1618-1663)
•Discussed Diffraction. (Newton also discussed
with human hairs but fail to explain)
•Actually both failedto explain diffraction.
•Denies Newton.
•Light is Fluid.
گور این

16. For about 100 years the situation remained
the same
•No evidence was found for light to be particle,
wave or fluid.

17. FINALLY
•Speed of light is measured

18. First attempt was made by Galileo
•In 1638

19. Ole Roemer (1644-1710)
•In 1675 Accidentally
•Wanted to measure the time of rotation of IO
moon of Jupiter.
•IO orbits Jupiter in 1.76 days
•Observed different times in different months.

20. Doppler Effect
•Earth Moving Towards Jupiter
Time Decreases
Earth Moving away Jupiter
Time Increases
•Got 2.11 * 10^8 m/s

21. James Bradley (1693-1762)
•In 1728 Accidentally
•Was observing motion of stars by using telescope
•Set Telescope on the chimneyof house of his friend
Molyneux.
•Used to rotate the telescope. Then found Doppler
effect.
•Got 3.01 * 10^8 m/s 2.95 * 10^8 m/s

22. Fizeau(23,Sep 1819 –18, Sep 1896)
Foucault (18,Sep 1819 –11, Feb 1868)

23. Mirror at 8.633 km
Got 3.01 * 10^8 m/s

24. Foucault
•Measured the speed of light in water
•Got ¾ time the speed of light in air.

25. Thomas Young (1773-1829)
•Got Doctor of Medicine Degree in 1796
•Changed interest in physics. Started Publishing
papers from 1799
•But have special role in medicine too. Child dose,
appendix etc.
•Worked on Music (Tuning Instrument)
•Explain Diffractionbut credit to Grimaldiin his book.

26. Thomas Young (1773-1829)
•Gave hypothesis of Vision and Color Theoryand
proved by Helmholtz that it’s Retina function(Young-
Helmholtz Theory)

27. Thomas Young (1773-1829)
•Gave InterferencePhenomena and proved Light is
wave in 1801.

28. James Clerk Maxwell (1831-1879)
•In 1922, In Cambridge, a host asked to Einstein, you
have done a lot on the shoulder of Newton. He said
but on the shoulder of Maxwell.
•In 1873, Proved Theoretically Light is wave,
composed of electric and magnetic field.

29. Max Planck (1858-1947)
•Theoretical Physicist
•In1900, Gave Particle Theory of Light
(Quanta)

30. Max Planck (1858-1947)

31. Albert Einstein (1879-1955)
•In1905, Proved Particle Theory
of Light (Quanta) Of Max Planck
experimentally. (Photon)

32. یگ نب قفانم یھب ینشور راک رخآ
DUAL NATURE