Inventions — Set 6

Correct Answer: A. Anders Celsius

• **Anders Celsius** = Anders Celsius proposed his 100-degree scale in 1742, defining 0 as the boiling point of water and 100 as the freezing point; the scale was reversed after his death to its present form (0 = freezing, 100 = boiling). • **1742** — The scale was renamed 'Celsius' in 1948 to honour him; it is the standard temperature scale used in science and daily life in most of the world. • 💡 Wrong-option analysis: Lord Kelvin: defined the absolute thermodynamic temperature scale (Kelvin) where 0 K = absolute zero (−273.15°C); Isaac Newton: proposed an early temperature scale with 0 at freezing and 33 at boiling, but it was not adopted; Daniel Fahrenheit: invented the mercury thermometer and the Fahrenheit scale (32°F freezing, 212°F boiling).

Correct Answer: C. Zacharias Janssen

• **Zacharias Janssen** = Zacharias Janssen, a Dutch spectacle maker, is generally credited with assembling the first compound microscope around 1590 by aligning two convex lenses in a tube, achieving magnification of up to 9×. • **~1590** — Janssen's compound microscope combined an objective lens and an eyepiece lens — the same two-lens configuration used in modern light microscopes — making it the first optical instrument to explore the microscopic world. • 💡 Wrong-option analysis: Robert Hooke: used a compound microscope to observe cells and published 'Micrographia' in 1665, coining the word 'cell'; Antonie van Leeuwenhoek: crafted single-lens microscopes of extraordinary quality (up to 270×) and was the first to observe bacteria and protozoa; Galileo Galilei: adapted telescope optics to make a compound microscope in 1609 but did not invent the first one.

Correct Answer: B. David Bushnell

• **David Bushnell** = David Bushnell built the Turtle in 1775, the first submarine to be used in combat — a hand-cranked, egg-shaped wooden vessel designed to attach a time bomb to the hull of a British warship during the American Revolution. • **1775** — The Turtle was the first submarine to use a screw propeller for underwater propulsion; it attempted to attack HMS Eagle in New York Harbour in 1776 but failed to drill into the ship's copper-sheathed hull. • 💡 Wrong-option analysis: Robert Fulton: built the Nautilus submarine in 1800 and the first commercially successful steamboat; John Holland: built the first modern military submarine accepted by the US Navy in 1900; Cornelis Drebbel: built the first navigable submarine in 1620 (in the Thames) but it was not used in combat.

Correct Answer: D. Lewis Waterman

• **Lewis Waterman** = Lewis Waterman patented the first reliable fountain pen in 1884, solving the chronic ink-flooding and drying problem with a three-fissure capillary feed channel that delivered ink smoothly while allowing air into the reservoir. • **1884** — Waterman designed his pen after a faulty earlier pen leaked on an important contract, ruining the deal; his capillary feed system remained the standard design for all fountain pens. • 💡 Wrong-option analysis: Laszlo Biro: invented the ballpoint pen in 1938, a different writing instrument; John Loud: patented the first ballpoint pen in 1888 for marking leather — not a fountain pen; Samuel Morse: invented the electric telegraph and Morse code.

Correct Answer: C. Laszlo Biro

• **Laszlo Biro** = Laszlo Biro, a Hungarian journalist, invented the modern ballpoint pen in 1938 (patented 1943), using a tiny rotating ball bearing at the tip to transfer quick-drying viscous ink onto paper, eliminating the smearing and leaking of fountain pens. • **1938** — Biro's pen used newspaper printer's ink (which dried quickly) instead of fountain pen ink; 'Biro' became a generic word for ballpoint pen in many countries, and the British Royal Air Force adopted it during World War II because it worked at high altitude. • 💡 Wrong-option analysis: Alexander Graham Bell: invented the telephone in 1876; Lewis Waterman: invented the reliable fountain pen in 1884, a different instrument using liquid ink; Christopher Sholes: invented the typewriter with the QWERTY keyboard.

Correct Answer: A. Elias Howe

• **Elias Howe** = Elias Howe patented the first practical lockstitch sewing machine in 1846, using an eye-pointed needle (hole near the tip, not the end) and a shuttle to form the interlocking stitch on both sides of the fabric. • **1846** — Howe's key innovation was the eye-at-the-point needle which passed thread through the fabric in one motion; Isaac Singer later added a foot pedal and continuous cloth feed, making it practical for home use. • 💡 Wrong-option analysis: Eli Whitney: invented the cotton gin (1793) and pioneered interchangeable parts manufacturing; James Watt: improved the steam engine; Isaac Singer: commercially popularised the sewing machine with improvements but Howe's 1846 patent was the first practical design.

Correct Answer: C. Gaston Plante

• **Gaston Plante** = Gaston Planté invented the lead-acid rechargeable battery in 1859 using lead plates immersed in sulfuric acid solution; passing current in reverse replenishes the chemical energy, making it the first rechargeable (secondary) battery. • **1859** — Lead-acid batteries can deliver very high current surges, making them ideal for starting car engines; they are still the most widely used rechargeable battery for automotive applications today. • 💡 Wrong-option analysis: Alessandro Volta: invented the voltaic pile (first primary battery) in 1800, which cannot be recharged; Thomas Edison: invented the nickel-iron alkaline storage battery in 1901 as a competitor to lead-acid; Michael Faraday: discovered electromagnetic induction and Faraday's laws of electrolysis.

Correct Answer: C. Michael Faraday

• **Michael Faraday** = Michael Faraday built the first device demonstrating electromagnetic rotation in 1821 — a wire carrying current rotated continuously around a magnet — which is the fundamental principle of the electric motor. • **1821** — Faraday's motor was a proof-of-concept that converted electrical energy into continuous mechanical rotation; practical commercial motors were developed from his principle over the following decades. • 💡 Wrong-option analysis: James Clerk Maxwell: formulated the mathematical theory of electromagnetism but was born in 1831, after Faraday's invention; Nikola Tesla: invented the practical AC induction motor in 1887–1888; Andre-Marie Ampere: developed the mathematical theory of the relationship between magnetism and current (Ampere's law).

Correct Answer: C. Eli Whitney

• **Eli Whitney** = Eli Whitney invented the cotton gin in 1793, a machine that used rotating wire teeth to pull cotton fibres through narrow slots, separating them from the seeds 50 times faster than hand-picking. • **1793** — Whitney's gin could process 23 kg of cotton per day versus 1 kg by hand; it transformed the American South's cotton industry, making cotton enormously profitable and dramatically increasing the demand for slave labour. • 💡 Wrong-option analysis: Cyrus McCormick: invented the mechanical reaper (grain harvester) in 1831; Samuel Slater: brought British textile spinning machinery designs to America, helping launch the US textile industry; John Deere: invented the self-scouring steel plough in 1837.

Correct Answer: A. Willis Carrier

• **Willis Carrier** = Willis Carrier designed the first modern air conditioning system in 1902 for a printing plant in Brooklyn, New York, controlling both temperature and humidity to prevent paper from expanding and contracting. • **1902** — Carrier's system cooled air by passing it over chilled coils and dehumidified it simultaneously; he founded the Carrier Corporation in 1915 and is recognised as the 'Father of Modern Air Conditioning.' • 💡 Wrong-option analysis: Carl von Linde: developed industrial refrigeration technology in 1876 using liquid ammonia, which was a precursor to air conditioning but not an AC unit; Frederick McKinley Jones: invented the first portable refrigeration system for trucks and trains in 1940; Nikola Tesla: pioneered AC electrical power but had no role in inventing air conditioning.