Tag: science & technology

Joule is the SI unit of energy, work, and heat. While option C lists 'Heat', the joule is more broadly a unit of all forms of energy including heat energy, mechanical work, and other energy forms. The question asks for the unit of joule, and heat is one form of energy measured in joules.

1 gram weight is the force exerted by 1 gram mass under standard gravity. Since 1 dyne = 10^-5 newtons and g = 9.81 m/s², 1 gram weight = 1g × 9.81 m/s² = 981 dynes.

1 Joule = 10^7 ergs. The erg is the CGS unit of energy, while joule is the SI unit. The conversion is: 1 J = 1 kg × 1 m²/s² = 1000 g × 10000 cm²/s² = 10^7 g×cm²/s² = 10^7 ergs.

Ampere is the SI unit of electric current. Ohm measures resistance, watt measures power, and neither of these is the unit of current.

A seismograph is the instrument used to measure and record earthquake intensity and ground motion. A barometer measures atmospheric pressure, a hydrometer measures liquid density, and a polygraph measures physiological responses.

The Centigrade (Celsius) and Fahrenheit scales give the same reading at -40 degrees. Using the conversion formula F = (9/5)C + 32, setting F = C gives C = (9/5)C + 32, which solves to C = -40.

T.H. Huxley famously described protoplasm as the 'physical basis of life' in the 19th century, emphasizing its fundamental role in living organisms. Leeuwenhoek was an early microscopist who discovered microorganisms, while Virchow is known for 'omnis cellula e cellula' (all cells come from cells). J.C. Bose contributed to plant physiology but did not work on protoplasm theory.

Nicolaus Copernicus formulated the heliocentric model in the 16th century, placing the Sun at the center of our solar system. This revolutionary idea replaced the geocentric (Earth-centered) model that had dominated for centuries. Newton later developed laws of motion and gravitation, Dalton worked on atomic theory, and Einstein developed relativity theory.

Alexander Fleming discovered penicillin in 1928 from the Penicillium mold, revolutionizing medicine with the first antibiotic. X-rays were discovered by Wilhelm Roentgen, streptomycin was discovered by Selman Waksman, and the telephone was invented by Alexander Graham Bell.