Barometer: Know Definition, Diagram, History, Working, Types & Applications

A barometer is an instrument used to measure atmospheric pressure. Atmospheric pressure, or air pressure, is the weight of the air above us and is a key factor in weather patterns, including storms, high pressure, and low pressure systems. Barometers are essential tools in meteorology, aviation, and other scientific fields, as they help to monitor changes in atmospheric pressure, which can indicate changes in the weather. A barometer measures the pressure exerted by the atmosphere. When the atmospheric pressure increases, it pushes the liquid in the barometer tube higher, and when the pressure decreases, the liquid level drops. Barometers are usually calibrated to read in units like millimetres or inches of mercury (mmHg or in Hg), or Pascals (Pa) for more precise measurements. A Barometer is a device that measures the air pressure at a specific temperature. It is a scientific tool that is useful for determining barometric pressure, which is the measurement of atmospheric pressure.

In this article, we will discuss more about barometer’s types, working principle, uses and how to make one.

What is a Barometer?

A barometer is a device for monitoring atmospheric pressure, Barometer is used to measure weather forecasting and altitude calculations. It is used to gauge air pressure as it changes with altitude, either above or below sea level. It was created in 1643 by the Italian scientist E. Torricelli. By placing the mercury in the vacuum, he was able to study its properties. He created the first barometer based on his theory. Evangelista Torricelli is typically credited with creating the barometer in 1643, while Gasparo Berti of Italy and René Descartes of France recorded an attempt to measure air pressure in 1631 and 1640, respectively. The first mercury barometer was undoubtedly created by Torricelli, while there is some debate as to who created the first water barometer.

Fig-Diagram of Barometer

History of Barometer

In 1643, Evangelista Torricelli, an Italian physicist and mathematician, made a groundbreaking discovery that led to the invention of the first barometer. Torricelli, a student of Galileo Galilei, was intrigued by the problem of water pumps, which could only lift water to a height of about 32 feet. He hypothesized that the weight of the atmosphere was responsible for this limitation. To test his hypothesis, Torricelli filled a long glass tube with mercury, a dense liquid, and inverted it into a dish of mercury. To his surprise, the mercury did not completely drain from the tube, but rather stood at a height of about 30 inches. Torricelli realized that the weight of the mercury column in the tube was balanced by the weight of the atmosphere pressing down on the mercury in the dish.

Torricelli's experiment demonstrated the existence of atmospheric pressure and provided a way to measure it. His mercury barometer, also known as a Torricellian tube, became the standard instrument for measuring atmospheric pressure for centuries.

Working of Barometer 

A tall closed tube placed upside-down in a mercury bath, which is a thick liquid metal at room temperature, creates the basic kind of barometer, with the liquid rising partially up the tube like it does in a thermometer. We use mercury instead of water for barometers because it is denser. Since water is less dense than mercury, it will be lifted up a tube by air pressure much greater than the same volume of mercury since it is less heavy. Modern barometers display the pressure measurement with accuracy and precision on an LCD display and are entirely electronic.

Types of Barometer

There are two categories of barometers used to gauge atmospheric pressure. Both types employ various techniques for determining air pressure and energy. Below are the two barometers.

• Mercury Barometer
• Aneroid Barometer

Mercury Barometer

The most often used barometer is this one. It consists of a mercury-filled glass column with inch markings on it. Its bottom end is resting in the mercury-filled cup with its top-end closed, or cistern. These barometers are gravity and environment-corrected for greater accuracy. The density of this mercury justifies its use. The cylindrical tube is encircled by a shallow, spherical dish in which the mercury is placed. This will automatically adjust to match the air pressure over the dish. The mercury is propelled up the tube as the strain increases. This is distinguished by a series of estimates which show the number of environments or bars. The above diagram is a mercury barometer.

Aneroid Barometer

The barometer is made of liquid. It comprises the aneroid capsule, a light, flexible metal box made of an alloy. This alloy contains copper and beryllium. The box is hermetically sealed to allow for greater stretching of the levers and springs due to changes in atmospheric pressure outside the box.

It is made of a fluid-filled aneroid capsule, a thin, flexible metal box made of a beryllium and copper alloy. improved expansion and contraction of the box’s levers and springs, which were created as a result of changes in atmospheric pressure outside the metal box’s tight seal.

Difference between Barometer and Manometer

The differences between barometer and manometer have been discussed below.

Parameters	Barometer	Manometer
Invented	In 1643, the barometer was established.	In 1661, the manometer was developed.
Inventors	Evangelista Torricelli	Otto von Guericke
Uses	Scuba divers use it to monitor their air tanks or for measuring atmospheric pressure and weather forecasting. In smartphone fitness apps, as well as in the GPS chips for quicker locks and altitude data transfer.	A lesser or larger magnitude of pressure variations is measured. Water pressure measuring and gas pressure tracking in water pipelines. In research labs and power plants.
Advantages	Low vapour pressure, a concentrated population, and a modest rate of evaporation.	Lower costs and maintenance Possibility of manufacturing, outstanding sensitivity and accuracy.
Disadvantges	While certain barometer types are portable, others are not, which increases the potential of liquid contamination.	Levelling is necessary. Poor dynamic performance is the result of condensation, which also leads to errors.

How to Make a Barometer?

What you’ll need to make a barometer is a coffee container or jar and a rubber band, a cocktail or pin stick, tape, glue, straw, and paper.

Procedure:

• A small amount of inflation will cause the balloon to burst; the more air within the balloon, the higher the pressure outside.
• Cut the knot end off and let the air out of the balloon.
• Use tape or an elastic band to secure the balloon in place snugly over the container after stretching it over it.
• Attach the straw’s end with tape or glue to the balloon’s centre, and then tape a pin or cocktail stick to the end.
• Mark the location of the pin on a card and tape it behind the barometer.
• Take a few days off and observe any changes. Keep track of the daily weather conditions and how they impact the barometer.

Uses of Barometer

• It is used in science and industry to measure weather.
• It is used in watches and mobile devices.
• This tool can be used to measure altitude.
• There are portable instruments that use aneroid barometers.
• Altimeters for aircraft employ aneroid barometers.
• Since atmospheric pressure and elevation are intimately correlated, GPS software uses the barometer in smartphones to determine the height the device is at.

You can also check other Physics topics too. Keep checking the Testbook for all the most recent information on various exams. Join the Testbook app today to take advantage of their thorough and trustworthy study resources, together with the assistance of Testbook specialists, to pass your desired competitive exam. Utilize great promotions by downloading the freeTestbook app right away.