Measuring Devices and Scales Notes with PDF

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Scientific Instruments & Technologies: A Structured Overview

1. Sound & Acoustics

• SONAR (Sound Navigation and Ranging)
  • Use: Locating submerged objects (e.g., submarines, icebergs), primarily by navigators. Measures depth (a specific application is a Fathometer).
  • Principle: Emits ultrasonic waves that bounce off objects to determine location and distance.
• Audiometer
  • Use: Measures the intensity of sound.
• Phonometer
  • Use: Measures the loudness of sound, specifically of the human voice.
• Audiophone
  • Use: A hearing aid device.

2. Weather & Atmosphere

• Anemometer
  • Use: Measures wind velocity (speed) and force.
• Barometer / Barograph
  • Use: Measures atmospheric pressure. A barograph records continuous changes.
  • Note: A simple barometer uses mercury. A sudden drop in mercury indicates an approaching thunderstorm.
• Hygrometer
  • Use: Measures relative humidity in the air.
• Raingauge
  • Use: Measures the amount of rainfall.
• Wind Vane
  • Use: Shows wind direction.

3. Heat, Temperature & Radiation

• Pyrometer (Radiation Thermometer)
  • Use: Measures very high temperatures (above 1500°C – 2000°C) without physical contact (e.g., the sun’s temperature).
  • Principle: Detects infrared or visible radiation, following the Stefan-Boltzmann law.
    • Total Radiation Pyrometer: A specific type capable of measuring up to 2000°C.
• Pyrheliometer
  • Use: Measures direct solar radiation.
• Pyranometer
  • Use: Measures total solar radiation (both direct and diffuse).
• Geiger Counter
  • Use: Detects radiation.

4. Light & Electromagnetic Waves

• Photometer / Luxmeter
  • Use: Measures the intensity or brightness of light.
• Ondometer
  • Use: Measures the frequency of electromagnetic waves.
• Colorimeter
  • Use: Measures the concentration of a substance in a solution by its color.

5. Electricity & Electronics

• Ammeter
  • Use: Measures electric current in a circuit (in Amperes). It does not measure electric power.
• Voltmeter
  • Use: Measures electrical potential difference (voltage).
• Potentiometer
  • Use: Measures electromotive force (voltage) in a circuit.
• Galvanometer
  • Use: Detects the presence of electric current.
• Ohm (Ω)
  • Use: The unit of electrical resistance.
• Capacitor
  • Use: Stores electrical energy.
• Junction Diode
  • Use: Used as a rectifier (converts AC to DC). It is not used as an amplifier.
• Bipolar Junction Transistor (BJT)
  • Use: Used as an amplifier. It is not used as a rectifier.
• Thermoresistor
  • Use: A type of electronic thermometer that changes its electrical resistance with temperature.

6. Pressure & Density Measurement

• Manometer
  • Use: Measures the pressure of gases or liquids.
  • Barometer is a specific type for atmospheric pressure.
• Hydrometer
  • Use: Measures the density (specific gravity) of liquids.
• Lactometer
  • Use: A type of hydrometer that measures the density of milk.
• Butyrometer
  • Use: Measures the fat content in milk and milk products.
• Spring Balance
  • Use: Measures weight by measuring the tension of a spring.

7. Distance, Surveying & Navigation

• Odometer
  • Use: Measures the distance covered by motor vehicles.
• Tacheometer
  • Use: A surveying instrument for quick measurement of distance to a target. It is not used for measuring pressure difference.
• Sextant
  • Use: Used in navigation for measuring angles.
• Theodolite
  • Use: Measures angular distances (elevation and azimuth) in surveying.
• Altimeter
  • Use: Measures height or altitude above a fixed level.
• Chronometer
  • Use: A highly accurate timekeeping device.

8. Medical & Biological Instruments

• Sphygmomanometer
  • Use: Measures blood pressure.
• Stethoscope
  • Use: Used to listen to heart sounds.
• Cardiograph
  • Use: Records the movement of the heart.
• Electroencephalogram (EEG)
  • Use: Monitors the electrical activity of the brain.
• Kymograph
  • Use: Records changes in pressure (e.g., blood pressure) over time.
• Polygraph
  • Use: Lie detector; monitors physiological indicators like blood pressure, pulse, and skin conductivity.
• Rh factor
  • Note: A term associated with blood groups, not an instrument.

9. Geophysics & Seismology

• Seismograph / Seismometer
  • Use: Detects, measures, and records the amplitude of seismic waves generated by earthquakes.
  • Note: It is incorrectly matched with “curvature of surface.”
• Richter Scale
  • Use: Measures the intensity or magnitude (energy released) of an earthquake. It is not used to measure humidity.

10. Other Specialized Instruments

• Gyroscope
  • Use: Measures or maintains orientation and angular velocity.
• Carburetor
  • Use: A device in internal combustion engines that mixes air and fuel.
• Crescograph
  • Use: Measures plant growth (invented by Sir Jagadish Chandra Bose).
• Caratometer
  • Use: Checks the purity (carat) of gold.

Key Technologies

• RADAR (Radio Detection and Ranging)
  • Use: Uses radio waves to determine the presence, location, and speed of objects like aircraft and ships.
• SONAR (Sound Navigation and Ranging)
  • Use: Uses ultrasonic waves to detect, locate, and measure the distance of underwater objects.

Know More About Measuring Devices and Scales:

• Measuring Devices and Scales – Old Year Questions
• Measuring Devices and Scales One Liner Questions & Answers