Science & Technology GK Questions with Answers – Page 11

Milling on a computer-controlled machine is a subtractive process: a rotating cutter removes material from a solid block until the shape remains, so no layers are added.

An STL file describes the outer surface of a three-dimensional object as a mesh of triangles and carries no colour, material or texture information.

He invented stereolithography in the mid-1980s, in which a laser hardens liquid photopolymer resin point by point, and in doing so built the first working 3D printer; he also went on to found a company to sell the machines.

The name comes from the method: material is added layer upon layer under the control of a digital model until the object is complete, so that nothing has to be cut away.

He persuaded the Tata trusts to fund the Tata Institute of Fundamental Research at Bombay in 1945, became the first chairman of the Atomic Energy Commission set up in 1948, and founded the Atomic Energy Establishment at Trombay, which was renamed the Bhabha Atomic Research Centre after he died in…

He led the introduction of the high-yielding dwarf wheat varieties into Indian fields in the nineteen sixties, worked with the government on the package of seed, fertiliser and irrigation that turned the country from food imports to self-sufficiency, and received the first World Food Prize in 1987.

Meghnad Saha showed in 1920 how the degree to which a gas is ionised depends on its temperature and pressure, and the equation let astronomers read the temperature of a star directly from the lines in its spectrum and so classify stars in a physically meaningful way; it is counted…

He was born on 22 December 1887 at Erode, worked largely without formal training, and left results on infinite series, continued fractions, partitions and the mock theta functions that mathematicians are still developing; he worked with G. H. Hardy at Cambridge and was elected a Fellow of the Royal Society.

Mokshagundam Visvesvaraya was born on 15 September 1861, served as Diwan of Mysore, designed the automatic sluice gates used at the Krishna Raja Sagara dam and the block system of irrigation, planned flood protection for Hyderabad, and received the Bharat Ratna in 1955; the day is observed as Engineer Day…

He developed the probe that made DNA fingerprinting practicable in India at the Centre for Cellular and Molecular Biology at Hyderabad, where the first Indian case used the technique in 1988; he later founded the Centre for DNA Fingerprinting and Diagnostics and served as Vice-Chancellor of Banaras Hindu University.

He designed the crescograph, which magnifies the growth of a plant many thousand times so that it can be recorded, and used it and related instruments to argue that plants respond to light, heat, touch and other stimuli much as animals do.

Khorana shared the Nobel Prize in Physiology or Medicine in 1968 with Robert Holley and Marshall Nirenberg for showing how the sequence of nucleotides in nucleic acids specifies the amino acids of a protein; he later synthesised the first artificial gene, a landmark in molecular biology.

Subrahmanyan Chandrasekhar showed, while still in his twenties, that a white dwarf heavier than about 1.44 times the mass of the Sun cannot be held up by the pressure of its degenerate electrons and must collapse further; the figure is called the Chandrasekhar limit, it underlies the modern account of…

He founded the Physical Research Laboratory at Ahmedabad in 1947, convinced the government to set up the Indian National Committee for Space Research in 1962, picked Thumba near the magnetic equator for the first sounding rocket launch in November 1963, and led the organisation that became the Indian Space Research…

C. V. Raman announced on 28 February 1928 that when a beam of light passes through a transparent medium a small fraction of it is scattered with a shifted wavelength, which carries information about the molecules of the medium; the Government of India fixed National Science Day on that anniversary…

Chandrasekhara Venkata Raman received the Nobel Prize in Physics in 1930 for his work on the scattering of light and for the effect named after him, which he had demonstrated on 28 February 1928; he was the first Asian and the first person from a non-white country to win a…

A gravitational wave detector is an L-shaped interferometer whose two arms, each four kilometres long, are watched for the minute change in length produced when a wave from colliding black holes or neutron stars passes through the Earth.

Their instruments, such as the giant sundial called the Samrat Yantra and the hemispherical Jai Prakash Yantra, measured time, declination and the positions of the planets with shadow and sightline alone, and the Jaipur site was inscribed on the UNESCO World Heritage List in 2010.

At that point the gravitational pulls of the Sun and the Earth combine with the orbital motion so that a spacecraft keeps station with the Earth, and from there the Sun can be watched continuously without any eclipse or occultation.

AstroSat was launched on 28 September 2015 by PSLV-C30 from Sriharikota into a near equatorial low Earth orbit.