Friday, November 28, 2014

Acharya Jagadish Chandra Bose - Biography and Scientific Contribution

Jagadish Chandra Bose was born in Bikrampur, Bengal, (now Munshiganj District of Bangladesh) on 30 November 1858.

Bose joined the Hare School in 1869 and then St. Xavier's School at Kolkata. In 1875, he passed the Entrance Examination (equivalent to school graduation) of University of Calcutta and was admitted to St. Xavier's College, Calcutta. At St. Xavier's,  He received a bachelor's degree from University of Calcutta in 1879.

Bose wanted to go to England to compete for the Indian Civil Service. But his father sent  Bose to England to study Medicine at the University of London. However, he had to quit because of ill health. The odour in the dissection rooms is also said to have exacerbated his illness.

Then he secured admission in Christ's College, Cambridge to study Natural Science. He received the Natural Science Tripos and MA from the University of Cambridge and a BSc from the University of London in 1884. Among Bose's teachers at Cambridge were Lord Rayleigh, Michael Foster, James Dewar, Francis Darwin, Francis Balfour, and Sidney Vines. At the time when Bose was a student at Cambridge, Prafulla Chandra Roy was a student at Edinburgh. They met in London and became intimate friends.

Bose returned to India in 1885. Sir Alfred Croft, the Director of Public Instruction, appointed Bose officiating professor of physics in Presidency College. Presidency College lacked a proper laboratory. Bose had to conduct his research in a small 24-square-foot (2.2 m2) room. He devised equipment for the research with the help of one untrained tinsmith. The college routine was made as arduous as possible for him, so that he could not have the time he needed for investigation." After his daily grind, he carried out his research far into the night, in a small room in his college. The policy of the British government for its colonies was not conducive to attempts at original research. Bose spent his own money for making experimental equipment. Within a decade of his joining Presidency College, he emerged a pioneer in the incipient research field of wireless waves.

Bose's 60 GHz microwave apparatus at the Bose Institute, Kolkata, India.
His receiver used a galena crystal detector inside a horn antenna and galvanometer to detect microwaves. Bose invented the crystal radio detector, waveguide, horn antenna, and other apparatus used at microwave frequencies.

The first remarkable aspect of Bose's follow up microwave research was that he reduced the waves to the millimetre level (about 5 mm wavelength). He realised the disadvantages of long waves for studying their light-like properties.

During a  public demonstration at Town Hall of Kolkata, Bose ignited gunpowder and rang a bell at a distance using millimetre range wavelength microwaves. He said "The invisible light can easily pass through brick walls, buildings etc. Therefore, messages can be transmitted by means of it without the mediation of wires."

Bose's first scientific paper, "On polarisation of electric rays by double-refracting crystals" was communicated to the Asiatic Society of Bengal in May 1895. His second paper was communicated to the Royal Society of London by Lord Rayleigh in October 1895. In December 1895, the London journal the Electrician (Vol. 36) published Bose's paper, "On a new electro-polariscope". At that time, the word 'coherer', coined by Lodge, was used in the English-speaking world for Hertzian wave receivers or detectors. The Electrician readily commented on Bose's coherer. (December 1895). The Englishman (18 January 1896) quoted from the Electrician and commented as follows:

”Should Professor Bose succeed in perfecting and patenting his ‘Coherer’, we may in time see the whole system of coast lighting throughout the navigable world revolutionised by a Bengali scientist working single handed in our Presidency College Laboratory.”

In May 1897, two years after Bose's public demonstration in Kolkata, Guglielmo Marconi conducted his wireless signalling experiment on Salisbury Plain. Bose went to London on a lecture tour in 1896 and met Marconi, who was conducting wireless experiments for the British post office. In an interview, Bose expressed disinterest in commercial telegraphy and suggested others use his research work. In 1899, Bose announced the development of a "iron-mercury-iron coherer with telephone detector" in a paper presented at the Royal Society, London.

Bose's demonstration of remote wireless signalling has priority over Marconi.He was the first to use a semiconductor junction to detect radio waves, and he invented various now commonplace microwave components.In 1954, Pearson and Brattain gave priority to Bose for the use of a semi-conducting crystal as a detector of radio waves.Further work at millimetre wavelengths was almost non-existent for nearly 50 years. In 1897, Bose described to the Royal Institution in London his research carried out in Kolkata at millimetre wavelengths. He used waveguides, horn antennas, dielectric lenses, various polarisers and even semiconductors at frequencies as high as 60 GHz;much of his original equipment is still in existence, now at the Bose Institute in Kolkata. A 1.3 mm multi-beam receiver now in use on the NRAO 12 Metre Telescope, Arizona, US, incorporates concepts from his original 1897 papers.

Sir Nevill Mott, Nobel Laureate in 1977 for his own contributions to solid-state electronics, remarked that "J.C. Bose was at least 60 years ahead of his time. In fact, he had anticipated the existence of P-type and N-type semiconductors."

His major contribution in the field of biophysics was the demonstration of the electrical nature of the conduction of various stimuli (e.g., wounds, chemical agents) in plants, which were earlier thought to be of a chemical nature. These claims were later proven experimentally. He was also the first to study the action of microwaves in plant tissues and corresponding changes in the cell membrane potential. He researched the mechanism of the seasonal effect on plants, the effect of chemical inhibitors on plant stimuli and the effect of temperature. From the analysis of the variation of the cell membrane potential of plants under different circumstances, he hypothesised that plants can "feel pain, understand affection etc."

Bose performed a comparative study of the fatigue response of various metals and organic tissue in plants. He subjected metals to a combination of mechanical, thermal, chemical, and electrical stimuli and noted the similarities between metals and cells. Bose's experiments demonstrated a cyclical fatigue response in both stimulated cells and metals, as well as a distinctive cyclical fatigue and recovery response across multiple types of stimuli in both living cells and metals.

Bose documented a characteristic electrical response curve of plant cells to electrical stimulus, as well as the decrease and eventual absence of this response in plants treated with anaesthetics or poison. The response was also absent in zinc treated with oxalic acid. He noted a similarity in reduction of elasticity between cooled metal wires and organic cells, as well as an impact on the recovery cycle period of the metal.

On 14 September 2012, Bose's experimental work in millimetre-band radio was recognised as an IEEE Milestone in Electrical and Computer Engineering.

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