type: timeline | topic: history-of-experiments
| Year | Development | Significance |
|---|---|---|
| ~1638 | Galileo discovers pendulum isochronism | T independent of amplitude and mass — foundation of pendulum clock |
| 1679 | Hooke's Law: F = kx | Foundation for Young's modulus experiments; stress-strain relationship |
| 1798 | Henry Cavendish uses torsion balance | Precise measurement of G; same principle as Wheatstone bridge (null method) |
| 1833 | Wheatstone bridge circuit invented | Basis of metre bridge used in NEET experiments today |
| 1845 | Gabriel Stokes derives drag formula | = 2(ρ−σ) — experimental method to measure viscosity |
| 1850s | Vernier scale popularized | Pierre Vernier (1631): enabled sub-division readings beyond main scale |
| 1862 | Maxwell derives electromagnetic theory | Predicts speed of light; sound speed measurable by resonance methods |
| 1904 | Fleming discovers thermionic effect | Precursor to p-n junction diodes; I-V characteristic concept established |
| 1947 | Shockley, Bardeen, Brattain invent transistor | p-n junction theory formalized; Si and Ge thresholds experimentally established |
| 1957 | Zener diode commercialized | Voltage regulation using reverse breakdown — practical devices |
| 1962 | LED invented (Nick Holonyak Jr.) | Forward bias light emission; ≈ 1.5–3 V depending on material |
| 1980s | Semiconductor experiments in school labs | NEET-level I-V characteristic experiments standardized in curriculum |