Units, Instruments and Quick Facts
Units
| Quantity | SI unit | Quantity | SI unit |
|---|---|---|---|
| Force | newton | Pressure | pascal |
| Work, energy, heat | joule | Power | watt |
| Frequency | hertz | Charge | coulomb |
| Potential difference | volt | Resistance | ohm |
| Capacitance | farad | Magnetic field | tesla |
| Radioactivity | becquerel | Illumination | lux |
| Power of lens | dioptre | Sound intensity | decibel |
| Speed | m/s | Acceleration | m/s^2 |
| Momentum | kg m/s | Density | kg/m^3 |
| Wavelength | metre (also angstrom) | Distance of stars | light year |
Instruments
| Instrument | Use |
|---|---|
| Barometer | Atmospheric pressure |
| Hygrometer | Humidity |
| Anemometer | Wind speed |
| Thermometer | Temperature |
| Pyrometer | Very high temperature |
| Seismograph | Earthquake |
| Sphygmomanometer | Blood pressure |
| Stethoscope | Heart and lung sounds |
| Lactometer | Purity of milk |
| Hydrometer | Density of liquids |
| Ammeter | Current |
| Voltmeter | Potential difference |
| Galvanometer | Detects small current |
| Altimeter | Altitude |
| Odometer | Distance travelled |
| Speedometer | Speed |
| Periscope | See above obstacles |
| Telescope | Distant objects |
| Microscope | Tiny objects |
| Spectrometer | Spectra |
| Dynamo | Mechanical to electrical |
| Radar | Locate objects by radio waves |
| SONAR | Underwater distances by sound |
| Cardiograph (ECG) | Heart's activity |
| Rain gauge (pluviometer) | Rainfall |
| Ultrasound | Scans inside the body |
Keep practising
Notes are only half the work. Test yourself with questions and discuss doubts with other aspirants.
Prepared for exam revision from the NCERT Science textbooks for Classes 6 to 10 and standard sources. Space missions, awards and records change, so check official sources for recent facts. Found a mistake? Tell us.