Sir C.V.Raman
p. 37 & 38 Question and Answers
2[a] Raman read three books written by three great personalities.
1. Light of Asia 2. The Elements of Euclid 3. The sensation of tone by Helmholtz.
These books had great influence on hom. They had profound effect on his working. The problems he chose to work and the nature of solutions he discovered.
2[b] He could not impress his teachers because he was quite unimpressive in appearance.
2[c] He said that because, his main interest was studying physics. The medical test in which he was disqualified became a boon for he could study physics.
2[d] It became a historic day because this was the place where he and his team performed the legendary experiment on light.
2[e] He discovered that water molecules could scatter light just like air molecules. It was a great thing in those days. It became important to him because that set him on the track to discovering the famous Raman Effect in 1923.
2[f] There he developed several ideas on resonance of sound. He took up violin for study and developed it.
Extra Questions
1. What is Raman Effect ?
When monochromatic light passes through a transparent medium some of the light is scattered. If the spectrum of this scattered light is examined, it is found to contain apart from light of the original wavelength weaker lines differing from this by constant amounts. Such lines are called Raman lines. They are due to the loss or gain of energy experienced by the photons of light. This takes place as a result of interaction with the vibrating molecules of the medium through which they pass.
2. Where do we use Raman Effect ?
Raman Effect is useful in the study of molecular energy levels.
3. What is Compton Effect ?
The reduction in the energy of a photon as a result of its interaction with a free electron. Part of photon’s energy is transferred to the electron and part is redirected as a photon of reduced energy.
[Arthur H. Compton : 1892 – 1962]
4. What is diffraction ?
When a beam of light passes through a slit dark bands are formed on the screen. This is a nature of wave propagation.
5. What is Quantum Theory ?
Energy exists in discrete units. The quantum of electromagnetic radiation is photon. In nuclear physics it is meson.
6. What did Rayleigh say ?
The blueness of the ocean is due to the reflection of the Sky.
7. What is corpuscular theory ?
The corpuscular theory says that the light travels in the form of particles.
8. What is fluorescence ?
It is a form of luminescence in ;which certain substances are capable of absorbing light of one wavelength and emitting light of another wave length.
9. What is resonance ?
If to a system capable of oscillation, a small periodic force is applied, the system is in general set into forced oscillations of small amplitude.
10. How is honourary doctorate is given ?
It is awarded by universities to those people who have contributed a lot in their field of profession. Eg. NTR for action; Smt Gandhi for politics.
11. What is acoustics ?
It is the study reflection of sound.
12. What was his contribution to society ?
He used to conduct seminars on science and explain science in such a lucid manner, that even a common man could understand them easily.
13. Where is Raman Effect used in spectroscopy ?
It is used in
1] surface enhance Raman Spectroscopy
2] Resonance “ ”
3] Surface enhance “ ”
4] Higher “ “
5] Spontaneous “ ”
6] Optical tweezers “ ”
7] Stimulated “ ”
8] Spatially offset “ ”
9] Coherent anti-stokes “ ”
10] Inverse “ ”
11] Tip enhanced “ ”
12] Transmission “ ”
13] Raman Optical Activity
14. What was the source of light Raman used ?
Raman used mercury arc as the source of light for his experiments.
15. What are the various types of scatterings?
1. Rayleigh scattering 2. Stokes scattering[ molecules absorbs energy] 3. Anti-stokes scattering
[ molecules lose energy]
16. To what scattering Raman Effect is related ?
Raman effect is related to Stoke’s and anti-stoke’s scatterings.
17. Explain stoke’s scattering.
It occurs when light impinges upon a molecule and interacts with the electron cloud and the bonds of that molecule. A photon excites the molecule from the ground state to a virtual energy state. When the molecule emits a photon and returns to the ground state it returns to a different rotational or vibrational state. The difference is emitted as a photon.
18. What are the applications of Raman Effect ?
1. chemical bonds and symmetry of molecules
2. in crystallography
3. low frequency excitations such as a] plasmas b] magnons c] superconducting
4. in nanowires
5. counterfeit drugs
6. mineral testing
7. liquid crystals
8. for manipulating a trapped ion’s energy levels
9. to study aerosols
19. What was the evidence for proving corpuscular theory of light ?
Raman had a hunch that if light did not exist as particles, or quanta the scattering experiment would show only a change in the light intensity of the light could change its frequency as well as intensity. He went ahead and found the evidence for corpuscular theory of light.
20. What do you mean by feeble fluorescence ?
Raman’s team worked on light scattering. That was a delicate experiment because the effect is very weak and it is difficult to be sure of the observation. That was why it was called fluorescence.
BIOGRAPHY:-
CV Raman was born on 8th Nov. 1888 in a village near Tiruchirapalli. He was physically weak. He was a lover of books. He was a voracious reader. There were three books which influenced him. He was very intelligent. So his teachers encouraged him to study ICS. Medical test in which he failed changed the course of his life.
He joined M.A. in Presidency College , Madras Calcutta
He joined Indian Association for the Cultivation of Science. Raman was fascinated by waves and sound. He built a violin own and studied sound.
Later he was fascinated by optics. He negated Rayleigh’s version for the blueness of the ocean. He proved that it is the refraction of light that is the cause of blueness of the ocean. He used quantum theory of light and conducted experiments on scattering of light in his own way. At last his team found out the feeble fluorescence which is called Raman Effect. For his great achievement he was awarded the Nobel Prize in Physics in 1930. He passed away in 1970.
BITS :-
1. Raman was born in a village near Tiruchirapalli.
2. Raman was born on 8th Nov. 1888.
3. Raman’s father was an athletic.
4. Raman was not physically very strong.
5. Books were to him like old friends.
6. The light Asia is Buddha.
7. The Elements of Euclid
8. The sensations of tone is on the properties of sound waves.
9. Raman did his B.A. from Presidency college, Madras
10. Raman’s teachers encouraged him to do ICS.
11. Raman did not qualify in medical test.
12. Medical test is the only test that Raman failed.
13. Raman did his M.A. from Presidency College , Madras
14. Raman got his results published in Philosophical Magazine of England.
15. Raman passed M.A. in 1907.
16. FCS stands for Financial Civil Services.
17. Raman worked as Assistant Accountant General, in Calcutta
18. Raman was fascinated by waves and sound.
19. He called his ideas ‘ remarkable resonance.’
20. He took ‘violin’ for studying sound.
21. Accoustics contimued to interest him.
22. Calcutta University
23. One of Raman’s disciple was Dr Suri Bhagavantam.
24. In 1922 Raman wrote an essay on “The Molecular Diffraction of Light”
25. The weak scattering was called “feeble fluorescence”
26. The day of Raman Effect is the National Science Day.
27. Raman received his Nobel Prize in 1930.
28. Raman took up the directorship of Indian Institute of Science, Bangalore
29. Raman retired in 1948.
30. Raman died on 21st Nov. 1970.
31. Raman edited “ Current Science.”
32. National Science Day falls on 28th February.
33. Raman was fascinated by Helmholtz’s ‘the sensations of tone.’
34.The journal “physical review” was published in USA.
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