PRELIMS

Electronics and Scientific References

Key Inventions and Inventors

• Aeroplane: Inventor: Wright brothers. Country: USA. Year: 1903
• Ball-point pen: Inventor: C. Biro. Country: Hungary. Year: 1938
• Computer: Inventor: Charles Babbage. Country: Britain. Year: 1834
• Diesel engine: Inventor: Rudolf Diesel. Country: Germany. Year: 1892
• Dynamite: Inventor: Alfred Nobel. Country: Sweden. Year: 1867
• Dynamo: Inventor: Michael Faraday. Country: England. Year: 1831
• Steam engine: Inventor: James Watt. Country: Scotland. Year: 1765
• Telephone: Inventor: A. Graham Bell. Country: USA. Year: 1876
• Television: Inventor: J.L. Baird. Country: Scotland. Year: 1926
• Transistor: Inventor: Bardeen & Shockley. Country: USA/UK. Year: 1949
• X-ray: Inventor: Wilhelm Roentgen. Country: Germany. Year: 1895

Important Discoveries

• Laws of Motion: Scientist: Newton. Year: 1687
• Atom: Scientist: John Dalton. Year: 1808
• Law of Floatation: Scientist: Archimedes. Year: 1827
• Electromagnetic Induction: Scientist: Michael Faraday. Year: 1831
• Periodic Table: Scientist: Mendeleev. Year: 1888
• Radioactivity: Scientist: Henry Becquerel. Year: 1896
• Quantum Theory: Scientist: Max Planck. Year: 1900
• Photoelectric Effect: Scientist: Albert Einstein. Year: 1905
• Raman Effect: Scientist: C.V. Raman. Year: 1928
• Neutron: Scientist: James Chadwick. Year: 1932

S.I. Units Reference

• Force: Unit: Newton. Symbol: . Quantity: Work/Energy. Unit: Joule. Symbol:
• Power: Unit: Watt. Symbol: . Quantity: Pressure. Unit: Pascal. Symbol:
• Charge: Unit: Coulomb. Symbol: . Quantity: Resistance. Unit: Ohm. Symbol:
• Potential Diff.: Unit: Volt. Symbol: . Quantity: Capacity. Unit: Farad. Symbol:
• Magnetic Flux: Unit: Weber. Symbol: . Quantity: Frequency. Unit: Hertz. Symbol:
• Luminous Flux: Unit: Lumen. Symbol: . Quantity: Illumination. Unit: Lux. Symbol:
• Wavelength: Unit: Angstrom. Symbol: . Quantity: Distance. Unit: Light year. Symbol:
• Solid Angle: Unit: Steradian. Symbol: . Quantity: Angle. Unit: Radian. Symbol:

Unit Conversions

• Length: 1 Inch = 2.54 cm; 1 Mile = 1.60 km; 1 Nautical Mile = 1.85 km; 1 Angstrom = m.
• Force/Energy: 1 Dyne = N; 1 Erg = J; 1 Horse Power (HP) = 746 Watt.
• Temperature: (Normal Body Temp). .

Semiconductors and Basic Electronic Devices

• Conductors: Low resistance, allow current flow easily (e.g., copper, silver).
• Insulators: Very high resistance, block current flow (e.g., rubber, glass).
• Semiconductors: Resistance between conductors and insulators; conductivity increases with temperature (opposite of metals). Examples: Silicon, Germanium.
  • Doping: Adding impurities to pure ("intrinsic") semiconductors to increase conductivity.
    • N-type: Doped with pentavalent impurity (e.g., Arsenic, Phosphorus); majority carriers are electrons.
    • P-type: Doped with trivalent impurity (e.g., Boron, Indium); majority carriers are holes.
• Diode: Formed by a P-N junction; allows current to flow in one direction only (rectification, converting AC to DC).
• Transistor: Three-terminal device (Emitter, Base, Collector) formed by two P-N junctions (NPN or PNP); used for amplification and switching.
• Logic Gates: Basic building blocks of digital circuits operating on binary (0/1) inputs — AND, OR, NOT, NAND, NOR, XOR gates.

Recent Developments: India's Semiconductor Mission

• India Semiconductor Mission (ISM): Launched 2021 under MeitY with an outlay of ₹76,000 crore to build a sustainable semiconductor and display ecosystem.
• Focus: Attracting fabrication ("fab") plants, chip design, and Outward/Assembly Testing Marking Packaging (OSAT/ATMP) units to India.
• Note: Exact figures for specific approved fabs are evolving; verify current details from official MeitY sources before quoting in an answer.

UPSC Relevance

Reference tables of units and instruments are high-yield for "Science in Daily Life" questions.

• Common Trap: Hydrometer (density) vs Hygrometer (humidity).
• Semiconductors: Doping types (N-type/P-type) and their majority carriers are standard S&T concepts.
• Units: Standard units like Lux (illumination) and Lumen (flux) are often asked in Match the Following formats.
• Policy: India Semiconductor Mission is a live current-affairs tie-in to basic semiconductor concepts.