Science and Technology, Part 1
Chapter 3 begins! Seven physics laws, twelve chemical formulae, eight famous scientists, and eighteen inventions and their inventors.
3.1 Laws of Physics
| Law | What it says |
|---|---|
| Law of reflection | The angle of reflection and the angle of incidence are equal. |
| Newton's first law of motion | A body at rest, or moving at constant speed in a straight line, stays that way unless a force acts on it. (Also called the "law of inertia.") |
| Boyle's law | If a gas is compressed at constant temperature, the product of its pressure and volume stays constant. |
| Ohm's law | The potential difference across a conductor equals the current × its resistance. |
| Charles's law | At constant pressure, the volume of a gas is directly proportional to its absolute temperature. |
| Pascal's law | Pressure applied anywhere in a fluid at rest is transmitted equally to every other part of the fluid. |
| Newton's third law of motion | To every action there is an equal and opposite reaction. |
Boyle's law — temperature stays the SAME; pressure and volume trade off (one up, one down). Charles's law — pressure stays the SAME; volume and temperature move TOGETHER (heat it, it expands). Memory hook: Boyle = Balance (temp fixed). Charles = Changes with temperature (pressure fixed).
Sir Isaac Newton also practised alchemy and wrote over a million words on the subject. After his death in 1727, the Royal Society deemed his alchemy papers "not fit to be printed." The papers were rediscovered in the mid-20th century, and most scholars now agree Newton was also an alchemist.
3.2 Chemical Names and Formulae
Twelve everyday substances — common name, proper chemical name, and formula.
| Common name | Chemical name | Formula |
|---|---|---|
| Washing soda | Sodium carbonate | Na₂CO₃·10H₂O |
| Water | Hydrogen oxide | H₂O |
| Lime water | Calcium hydroxide | Ca(OH)₂ |
| Gypsum | Calcium sulphate | CaSO₄·2H₂O |
| Baking soda | Sodium bicarbonate | NaHCO₃ |
| Laughing gas | Nitrous oxide | N₂O |
| Chloroform | Trichloromethane | CHCl₃ |
| Caustic soda | Sodium hydroxide | NaOH |
| Bleaching powder | Calcium hypochlorite | Ca(ClO)₂ |
| Blue vitriol | Copper sulphate | CuSO₄·5H₂O |
| Limestone | Calcium carbonate | CaCO₃ |
| Quick lime | Calcium oxide | CaO |
Washing soda = sodium carbonate (Na₂CO₃·10H₂O — the 2 balances sodium's +1 charge against carbonate's −2 charge). Baking soda = sodium bicarbonate (NaHCO₃) — a completely different compound. The names look similar, but "bi-" makes all the difference.
Calcium family (4): Lime water Ca(OH)₂, Gypsum CaSO₄, Limestone CaCO₃, Quick lime CaO — plus Bleaching powder Ca(ClO)₂, that's 5 total. Sodium/"soda" family (3): Washing soda, Baking soda, Caustic soda — all three literally have "soda" in the common name. Notice "·10H₂O" and similar — this means water molecules are built into the crystal structure ("water of crystallisation").
3.3 Renowned Scientists
Eight scientists — learn each as a tiny story: who, when, where, what.
| Scientist | Born | Known for |
|---|---|---|
| Charles Darwin | 1809, England | Theory of Natural Selection; wrote "The Origin of Species". |
| Louis Pasteur | 1822, France | Fermentation caused by micro-organisms; first rabies vaccine. |
| Albert Einstein | 1879, Germany | Theory of Relativity; Nobel Prize for the photoelectric effect. |
| John Dalton | 1766, England | Atomic Theory; also researched colour blindness (he was colour-blind himself). |
| William Harvey | 1578 | Discovered the heart works like a pump, circulating blood. |
| Michael Faraday | 1791, England | Link between electricity and magnetism — led to the electric motor and dynamo. |
| Thomas Edison | 1847, USA | Motion picture camera, phonograph, and more. |
| Alexander Fleming | 1881, Great Britain | Discovered penicillin. |
Einstein's 1921 Nobel Prize was for the Photoelectric Effect, NOT the Theory of Relativity — even though Relativity is what made him famous. One of the most commonly asked "gotcha" facts in GK exams.
Biology/Medicine: Darwin (evolution), Pasteur (germs/vaccines), Harvey (blood circulation), Fleming (penicillin). Physics/Chemistry: Einstein (relativity), Dalton (atomic theory), Faraday (electromagnetism), Edison (inventions).
After Einstein's death in 1955, his brain was removed by Thomas Harvey during the autopsy, without his family's permission. Years later, scientist Marian Diamond discovered Einstein had significantly more glial cells in the brain region responsible for synthesising information.
3.4 Inventions and Discoveries
Eighteen inventions and discoveries — the longest matching list in this chapter, so grouping by type is essential.
| Discovery / invention | Person |
|---|---|
| Oxygen (gas) | J. Priestley |
| Hydrogen (gas) | Henry Cavendish |
| Heavy hydrogen (deuterium) | Urey |
| Bacteria (first observed) | Leeuwenhoek |
| DNA (structure) | Watson and Crick |
| Vitamins (named) | Funk |
| Uranus (planet) | William Herschel |
| Rubber balloon | Michael Faraday |
| Hot air balloon | Montgolfier Brothers |
| Barometer | Torricelli |
| Steel (process) | Bessemer |
| Nylon | Wallace Carothers |
| Vacuum flask | James Dewar |
| Crescograph (plant growth measurer) | J. C. Bose |
| Sextant | John Hadley |
| Telegraph code (Morse code) | Samuel Morse |
| Logarithms | John Napier |
| Coca-Cola | Pemberton |
Chemistry — gases/matter (4): Oxygen (Priestley), Hydrogen (Cavendish), Heavy hydrogen (Urey), Bacteria (Leeuwenhoek). Biology (2): DNA (Watson & Crick), Vitamins (Funk). Astronomy (1): Uranus (Herschel). Flight and air (3): Rubber balloon (Faraday), Hot air balloon (Montgolfier Brothers), Barometer (Torricelli). Materials (3): Steel (Bessemer), Nylon (Carothers), Vacuum flask (Dewar). Instruments and codes (4): Crescograph (Bose), Sextant (Hadley), Telegraph code (Morse), Logarithms (Napier). Odd one out (1): Coca-Cola (Pemberton).
J. C. Bose invented the Crescograph, a device that measures plant growth — India's contribution to this list. Also: −40° is the one temperature where Celsius and Fahrenheit give exactly the same number.
Practice like the real exam
Ohm's law
False — washing soda is sodium carbonate; baking soda is sodium bicarbonate.
(b) Photoelectric Effect
J. C. Bose
−40 degrees
CaO
You did it! 🎉
🏁 GK Chapter 3 · Sections 3.1–3.4 · Prishita, Class 8