What is the Difference Between Barometer and Thermometer?

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A barometer and a thermometer are both scientific instruments used to measure different physical properties related to atmospheric conditions. Here are the key differences between the two:

  • Function: A barometer measures atmospheric pressure, while a thermometer measures temperature.
  • Temperature Measurement: Thermometers typically have a probe that is placed in the object being measured, such as food or drink, to measure its temperature. In contrast, barometers measure air pressure, which can be used to predict weather conditions.
  • Pressure Measurement: A barometer uses air pressure to measure atmospheric pressure, and it tells whether the pressure is rising or falling, indicating sunny and dry conditions or stormy and wet conditions, respectively.
  • Types of Thermometers: Thermometers can be based on water, mercury, or digital technology, with digital thermometers providing quick and accurate readings. Mercury or alcohol thermometers are used in the bulb of a thermometer, which expand and rise in the tube as the temperature increases, and can be used in various contexts, such as weather stations and medical applications.
  • Temperature Scale: The main units for calculating temperature are Kelvin, Celsius, and Fahrenheit, with the US using the Fahrenheit scale and the rest of the world using the Celsius scale.

In summary, a barometer measures atmospheric pressure and is used for weather forecasting, while a thermometer measures temperature and can be used in various contexts, from weather stations to medical applications.

Comparative Table: Barometer vs Thermometer

Here is a table comparing the differences between a barometer and a thermometer:

Feature Barometer Thermometer
Purpose Measures atmospheric pressure Measures temperature
Design Uses mercury or aneroid to measure pressure changes Uses mercury or alcohol in a bulb that expands when heated and contracts when cooled
Scale Measures pressure in inches of mercury (inHg), millibars (mb), or atmospheres (atm) Measures temperature in degrees Fahrenheit (°F) or Celsius (°C)
Measurement Reads change in volume of mercury or change in shape of aneroid Reads change in volume of liquid (mercury or alcohol) as it expands or contracts with temperature
Range Typically measures pressure changes within a specific range Measures temperatures within a wide range, from very cold to very hot
Notable Types Mercury Barometer, Aneroid Barometer, Water Barometer Liquid-in-Glass Thermometer, Bimetallic Thermometer, Digital Thermometer, etc.

A barometer measures atmospheric pressure using mercury or an aneroid, while a thermometer measures temperature using mercury or alcohol in a bulb that expands when heated and contracts when cooled.