Revision
Scientific Instruments and Their Uses
A compact, tabular revision of scientific and measuring instruments, what they measure or do, and the physical principle behind each, for CAPF Paper I General Science
CAPF wiki•3 min read•7 sections
At a glance
SubjectGeneral Science
RevisionGeneral ScienceInstrumentsPhysicsPaper 1
One screen per section. Cover the right column and test yourself. CAPF Paper I rewards clean recall of "instrument to use" pairs rather than derivations, so memorise the measured quantity and, where it helps, the working principle. For any instrument whose modern use has shifted, treat the entry as the classic textbook association and verify the latest.
| Instrument |
Measures / does |
| Ammeter |
Electric current (in amperes), connected in series |
| Voltmeter |
Potential difference (volts), connected in parallel |
| Galvanometer |
Small electric currents and their direction |
| Ohmmeter |
Electrical resistance |
| Potentiometer |
Compares EMF of cells; measures internal resistance |
| Wattmeter |
Electrical power |
| Tachometer |
Speed of rotation (RPM) of a shaft or wheel |
| Speedometer |
Speed of a vehicle |
| Odometer |
Distance travelled by a vehicle |
| Dynamometer |
Force, power or torque |
| Manometer |
Pressure of a gas or liquid |
| Barometer |
Atmospheric pressure (Torricelli's mercury barometer) |
| Sphygmomanometer |
Blood pressure |
| Instrument |
Measures |
| Thermometer |
Temperature |
| Pyrometer |
Very high temperatures (of furnaces, kilns) |
| Hygrometer |
Humidity (water vapour) in air |
| Anemometer |
Wind speed |
| Wind vane |
Wind direction |
| Rain gauge |
Rainfall amount |
| Altimeter |
Altitude (height above sea level), used in aircraft |
| Lactometer |
Purity (relative density) of milk |
| Hydrometer |
Relative density (specific gravity) of liquids |
| Instrument |
Use |
| Telescope |
Viewing distant objects (stars, planets) |
| Microscope |
Magnifying very small objects |
| Periscope |
Viewing over or around obstacles (submarines, trenches) |
| Kaleidoscope |
Producing symmetrical patterns by multiple reflection |
| Spectroscope |
Analysing spectra of light to identify elements |
| Stroboscope |
Viewing rapidly rotating or vibrating objects as if still |
| Endoscope |
Examining internal organs (medical) |
| Photometer |
Intensity of light |
| Instrument |
Records / detects |
| Seismograph |
Earthquake intensity and waves |
| Electrocardiograph (ECG) |
Electrical activity of the heart |
| Electroencephalograph (EEG) |
Electrical activity of the brain |
| Cardiograph |
Movements of the heart |
| Pyrheliometer |
Solar radiation intensity |
| Radar |
Detects and ranges distant objects using radio waves |
| Sonar |
Detects underwater objects using sound waves |
| Geiger counter |
Detects and measures radioactivity |
| Polygraph |
"Lie detector"; records physiological responses |
| Instrument |
Use |
| Gyroscope |
Maintains orientation; used in navigation and stabilisers |
| Sextant |
Measures the angular distance between two objects (navigation) |
| Theodolite |
Measures horizontal and vertical angles (surveying) |
| Carburettor |
Mixes air and petrol in internal combustion engines |
| Dynamo |
Converts mechanical energy into electrical energy |
| Transformer |
Steps voltage up or down in AC circuits |
| Refractometer |
Refractive index of a substance |
| Calorimeter |
Quantity of heat |
| Audiometer |
Measures hearing (intensity of sound) |
| Fathometer |
Measures ocean depth |
| Instrument |
Principle to recall |
| Barometer |
Atmospheric pressure balances a mercury column (~760 mm at sea level) |
| Hydrometer / lactometer |
Floats by Archimedes' principle; reads relative density |
| Galvanometer |
Magnetic effect of current deflects a coil |
| Radar |
Reflection of radio waves; echo timing gives range |
| Sonar |
Reflection of ultrasonic sound in water |
| Sextant |
Double reflection to measure angular elevation |