7 base units: King Met A Sad Tall Monkey Called — Kilogram, Metre, Ampere, Second, (kelvin) Temperature, Mole, Candela
SI Units of Physical Quantities
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Items to Memorize
- Length → metre (m)
- Mass → kilogram (kg)
- Time → second (s)
- Electric Current → ampere (A)
- Temperature → kelvin (K)
- Amount of Substance → mole (mol)
- Luminous Intensity → candela (cd)
- Force → newton (N)
- Energy → joule (J)
- Power → watt (W)
- Pressure → pascal (Pa)
- Frequency → hertz (Hz)
- Electric Charge → coulomb (C)
- Voltage → volt (V)
- Resistance → ohm (Ω)
Mnemonic Tricks
How It Maps
| Cue | Maps To |
|---|---|
| King (kg) | Mass → kilogram |
| Met (m) | Length → metre |
| A (A) | Current → ampere |
| Sad (s) | Time → second |
| Tall (K) | Temperature → kelvin |
| Monkey (mol) | Amount → mole |
| Called (cd) | Luminous Intensity → candela |
Why It Sticks
A sad tall monkey called by a king — bizarre royal court scene that captures all 7 SI base units with their symbols. The capitalization hints at which units use uppercase symbols.
Newton for force, Joule for energy, Watt for power that flows so free, Pascal presses, Hertz repeats, Coulomb charges, Volt completes, Ohm resists — physics is sweet!
Why It Sticks
Derived units paired with their quantity in a singable rhyme — each line connects name to function, not just symbol.
Frequently Asked Questions
What are the 7 SI base units?
Metre (length), Kilogram (mass), Second (time), Ampere (current), Kelvin (temperature), Mole (amount of substance), Candela (luminous intensity). All other units are derived from these seven.
How to remember all SI units quickly?
Base units: 'King Met A Sad Tall Monkey Called' (kg, m, A, s, K, mol, cd). Derived units: use the rhyme linking each unit to its quantity (Newton→force, Joule→energy, etc.).
What is the difference between base and derived units?
Base units are independently defined (7 total). Derived units are combinations: Newton = kg·m/s², Joule = N·m = kg·m²/s², Pascal = N/m², Watt = J/s.
Which SI unit has no dimension?
The radian (angle) and steradian (solid angle) are dimensionless SI units. The mole is a base unit but measures 'amount' (number of particles) rather than a physical dimension.
Are SI units important for JEE?
Yes — dimensional analysis using SI units is a powerful tool in JEE Physics. It helps verify formulas, derive relationships, and eliminate wrong options in MCQs.