SEMINARPresented by

Archana Babu

Contribution of an eminent scientist ..

Familiar Scientist’s

MeghNad Saha

( M.N Saha)

.

Life of Saha

Born of a lower middle class family in 1893 October 6.

Born in the village of Seoratali( Dacca, Bangladesh)

Fifth child of Jagannath Saha and his wife Bhuvaneswari.

CAREER

1905-1915

•Obtained many scholarships.•Completed MSc in applied mathematics

1916Joined as lecturer in Mathematics in

Calcutta University.Later transferred to Astrophysics.

RESEARCH PAPERS

Properties of electromagnetic waves

Theory of electronsElectrothermodynamics etc…

Sathyendranath Bose was his colleague.

They were familiar with the revolutionary developments:

Max Planck’s Quantum theoryNeils Bohr’s atom modelEinstein's theory of relativity etc.

CONTRIBUTIONSOF MEGHNAD

SAHA

Basic ideasThermal ionisation

Ionization potential

Bohr’s atom model

Spectra

Stellar spectra was a puzzle at that time.

•Agnes Clerke’s popular science books introduced Saha to these puzzles.

CONTRIBUTIONS

Saha theorized that due to extraordinary high temperature inside the sun and the stars, atoms get ionized and become positively charged.

•It occurs most frequently in the outermost layers of the sun and stars where pressure is comparatively low.

•The presence of different elements is different in different regions

•Using mathematical tools Saha developed a formula…..

Saha Ionization Equation

Log ( x2/1-x3 ) P = U/2/3 RT + 2.5 Log T – 6.5

X- fraction of ionised atom P- total pressure U- heat of ionisation R- universal gas constant T-temperature in kelvin

Calculated ionisation potential of Ca,Ba,Sr,H,He etc under various temperature and pressure.

STELLAR SPECTRA

Using this equation Saha was not only able to explain many aspects of solar spectrum, but also the varied nature of stellar spectra and give physical interpretation to the spectral sequence.

The four papers which obtained world wide reputation were:

Ionisation of the solar chromosphere.

( Thermal Ionisation Theory) On elements of the sun.On the problems of temperature-radiation of gases.

On the Harvard classification of stars.

(On a physical theory of stellar spectra)

Saha’s formula gave insight into the interior of the sun and stars, and their chemical compositions, densities of various elements and gravitational force on their surfaces.

OTHER CONTRIBUTIONS

Atomic and molecular spectroscopy

Nuclear physicsPropogation of radio waves

Age of rocks,water managementNational planning.

OTHER CONTRIBUTIONS

Also designed the device which detect the weight and stress of the sun rays.

MEGHNAD SAHA WAS A MAN WHO PREFERS PLAIN-SPEAKING AND NOTHING BUT THE TRUTH.