Physics: Fundamental Facts Every Student Must Know
Speed of light in vacuum: 3 × 10⁸ m/s (approximately 3,00,000 km/s)
Speed of sound in air (at 20°C): 343 m/s (sound travels faster in water and even faster in solids)
SI unit of force: Newton (N) — named after Sir Isaac Newton
SI unit of energy: Joule (J)
SI unit of power: Watt (W) — 1 Watt = 1 Joule per second
SI unit of electric current: Ampere (A)
SI unit of temperature: Kelvin (K) — absolute zero = 0 K = −273.15°C
Newton's Laws of Motion:
1. A body at rest remains at rest (Law of Inertia)
2. Force = Mass × Acceleration (F = ma)
3. Every action has an equal and opposite reaction
Archimedes' Principle: A body immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced. This explains why ships float.
Ohm's Law: Voltage (V) = Current (I) × Resistance (R)
Laws of Thermodynamics: Energy cannot be created or destroyed — only transformed (1st Law). Heat cannot spontaneously flow from a cold body to a hot body (2nd Law).
Electromagnetic Spectrum (wavelength order, longest to shortest): Radio waves → Microwaves → Infrared → Visible light → Ultraviolet → X-rays → Gamma rays
Exam tip: X-rays were discovered by Wilhelm Conrad Röntgen in 1895. Radioactivity was discovered by Henri Becquerel in 1896.
Chemistry: Key Facts and Important Elements
Atomic number of common elements:
- Hydrogen (H): 1 | Carbon (C): 6 | Nitrogen (N): 7 | Oxygen (O): 8
- Sodium (Na): 11 | Magnesium (Mg): 12 | Aluminium (Al): 13 | Silicon (Si): 14
- Iron (Fe): 26 | Copper (Cu): 29 | Zinc (Zn): 30 | Silver (Ag): 47
- Gold (Au): 79 | Mercury (Hg): 80 | Lead (Pb): 82 | Uranium (U): 92
Common chemical formulas:
- Water: H₂O | Table salt: NaCl | Carbon dioxide: CO₂
- Baking soda: NaHCO₃ | Washing soda: Na₂CO₃·10H₂O
- Plaster of Paris: CaSO₄·½H₂O | Bleaching powder: Ca(OCl)Cl
- Vinegar: CH₃COOH (Acetic acid) | Rust: Fe₂O₃ (Iron oxide)
pH Scale: 0–14. pH < 7 = acidic; pH = 7 = neutral; pH > 7 = alkaline/basic.
- Blood pH: ~7.4 (slightly alkaline) | Gastric acid: pH ~1.5–2 | Pure water: 7
States of Matter: Solid, Liquid, Gas, Plasma. Plasma is the fourth and most abundant state of matter in the universe (stars are made of plasma).
Periodic Table milestones: Dmitri Mendeleev published the first periodic table in 1869, arranging elements by atomic mass. Henry Moseley later rearranged elements by atomic number.
Alloys: Bronze = Copper + Tin | Brass = Copper + Zinc | Steel = Iron + Carbon | Stainless steel = Iron + Carbon + Chromium | Duralumin = Aluminium + Copper + Manganese + Magnesium
Biology: Human Body and Life Sciences
Human Body Facts:
- Total bones in human body: 206 (at birth: ~270–300, which fuse over time)
- Longest bone: Femur (thigh bone) | Smallest bone: Stapes (in the ear)
- Total muscles: ~640 | Total teeth in adults: 32
- Chambers in heart: 4 (two atria and two ventricles)
- Normal human blood pressure: 120/80 mmHg
- Normal body temperature: 37°C (98.6°F)
- Normal resting heart rate: 60–100 beats per minute
- Blood cells: RBC (carries oxygen; no nucleus in mature RBC), WBC (immune defence), Platelets (clotting)
- Blood groups discovered by: Karl Landsteiner (1900); Nobel Prize in 1930
- Universal blood donor: O− | Universal blood recipient: AB+
Vitamins and Deficiency Diseases:
| Vitamin | Also called | Deficiency Disease |
|---|---|---|
| A | Retinol | Night blindness |
| B1 | Thiamine | Beriberi |
| B3 | Niacin | Pellagra |
| B12 | Cobalamin | Pernicious anaemia |
| C | Ascorbic acid | Scurvy |
| D | Calciferol | Rickets (children), Osteomalacia (adults) |
| E | Tocopherol | Sterility, muscle weakness |
| K | Phylloquinone | Impaired blood clotting |
Richest natural source of Vitamin C: Amla (Indian gooseberry)
Vitamin D is synthesised by the body on exposure to sunlight.
Cell Biology: Cell theory proposed by Schleiden (1838) and Schwann (1839). DNA structure (double helix) discovered by James Watson and Francis Crick in 1953. DNA is found in the nucleus, mitochondria, and chloroplasts.
Taxonomy: Kingdom → Phylum → Class → Order → Family → Genus → Species. Humans: Kingdom Animalia → Phylum Chordata → Class Mammalia → Order Primates → Family Hominidae → Genus Homo → Species sapiens.
Space Science & ISRO: India's Achievements
Indian Space Research Organisation (ISRO):
- Founded: 15 August 1969 | Headquarters: Bengaluru
- Founder: Dr. Vikram Sarabhai (father of the Indian space programme)
- Current launch site: Satish Dhawan Space Centre (SDSC), Sriharikota, Andhra Pradesh
Key ISRO Missions:
| Mission | Year | Significance |
|---|---|---|
| Aryabhata | 1975 | India's first satellite (launched by USSR) |
| SLV-3 | 1980 | India's first indigenously built launch vehicle; Rohini satellite; led by APJ Abdul Kalam |
| INSAT-1B | 1983 | First operational INSAT; revolutionised Indian telecom & weather forecasting |
| IRS-1A | 1988 | India's first remote sensing satellite |
| PSLV-C1 | 1994 | First successful PSLV launch; became ISRO's workhorse rocket |
| Kalpana-1 | 2002 | Meteorological satellite; named after Kalpana Chawla after the Columbia disaster |
| Chandrayaan-1 | 2008 | First lunar mission; discovered water molecules on the Moon (using Moon Impact Probe) |
| Mangalyaan (MOM) | 2013 | First Mars mission; India became the first country to reach Mars orbit on its first attempt and at the lowest cost |
| ASTROSAT | 2015 | India's first dedicated multi-wavelength space observatory |
| Chandrayaan-2 | 2019 | Orbiter continues to function; Vikram lander crashed on landing |
| Chandrayaan-3 | 2023 | Successful soft landing on the Moon's south pole (23 August 2023) — India became the 4th country to land on the Moon and the FIRST to land near the south pole |
| Aditya-L1 | 2023 | India's first solar mission; studies the Sun from Lagrange Point 1 |
| Gaganyaan | Upcoming | India's first crewed space mission |
First Indian in space: Wing Commander Rakesh Sharma (1984), aboard Soviet Soyuz T-11. When Prime Minister Indira Gandhi asked how India looked from space, he replied: "Saare Jahan Se Achha."
Important space facts for exams:
- Nearest star to the Sun: Proxima Centauri (~4.24 light-years)
- Largest planet in the Solar System: Jupiter
- Smallest planet: Mercury (after Pluto was reclassified as a dwarf planet in 2006)
- Hottest planet: Venus (due to greenhouse effect, surface temperature ~465°C — hotter than Mercury)
- Planet with the most moons: Saturn (146 confirmed moons as of 2023)
- Red Planet: Mars | Blue Planet: Earth | Morning/Evening Star: Venus
Famous Scientists and Their Contributions
| Scientist | Nationality | Contribution |
|---|---|---|
| Isaac Newton | British | Laws of Motion, Universal Gravitation, Calculus |
| Albert Einstein | German-American | Theory of Relativity (E=mc²), Photoelectric effect |
| Marie Curie | Polish-French | Discovered Polonium & Radium; first woman to win Nobel Prize (twice) |
| Charles Darwin | British | Theory of Evolution by Natural Selection (On the Origin of Species, 1859) |
| Louis Pasteur | French | Germ theory of disease; pasteurisation |
| Alexander Fleming | British | Discovered Penicillin (1928) — world's first antibiotic |
| Gregor Mendel | Austrian | Father of Genetics; laws of heredity through pea plant experiments |
| CV Raman | Indian | Discovered Raman Effect (light scattering); Nobel Prize in Physics 1930 — first Asian to win Nobel in science |
| Jagadish Chandra Bose | Indian | Demonstrated that plants have feelings; pioneered radio science |
| APJ Abdul Kalam | Indian | Missile development (Agni, Prithvi); PSLV; 11th President of India (2002–2007) |
| Homi J. Bhabha | Indian | Father of Indian nuclear programme; founded TIFR and BARC |
| Srinivasa Ramanujan | Indian | Self-taught mathematical genius; contributions to number theory and infinite series |