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A barometer is an instrument used for measuring the atmospheric pressure of a given temperature. The device serves practical purposes such as weather forecasting and altitude calculation, making it a fascinating tool for those interested in meteorology or science.
- Barometer is also termed as a barometric pressure.
- The device will help determine the surface troughs, pressure systems and frontal boundaries.
- The word barometer is derived from the Greek báros, which means weight, and métron, which means measure.
- It was invented by the Italian scientist E. Torricelli in 1643.
- There are two types of barometer: mercury and aneroid barometer.
- You might confuse it with a clock, but it does not indicate time but tells us how the sky will be for the next few hours.
Key Terms: Barometer, Atmospheric Pressure, Mercury Barometer, Aneroid Barometer, Temperature, Types of Barometer, Pressure, Gravity, How does a Barometer Work
What is Barometer?
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The barometer is defined as a scientific device or instrument that is used to measure the atmospheric pressure of the earth. The atmosphere of the earth is wrapped up by several types of air layers, which have weights that press against everything in relation to gravity.
- The barometer is widely used by meteorologists for measuring the short term changes in the weather by the air pressure.
- It measures the atmospheric pressure in units of measurement called 'atm' or 'bars'.
- The average atmospheric pressure on the Earth's surface and sea level is between 940 and 1040 hPa and 1013 hPa, respectively.
- Divers use a submersible pressure gauge to determine the contents of the diver's air tank.
- A barometer is used for the measurement of pressure in aircraft.
Circular Analog Barometer Indicator
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How does a Barometer work?
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The barometer works on the basis of balancing the weight of mercury in the glass tube with reference to the atmospheric pressure. A plastic wrap is caved inside the glass tube by high atmospheric pressure.
- The straw and plastic sink taped segment resulted in the tilting of the end of the straw.
- If the weight of mercury in a glass tube is less than the atmospheric pressure, the mercury level rises.
- The mercury level lowers if the weight of mercury is more than the atmospheric pressure.
- This rise and fall of mercury helps measure atmospheric pressure using the marked line in the glass tube.
Types of Barometer
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Barometers are divided into two types for measuring the atmospheric pressure. Both types of methods are used to measure air pressure. The two barometers are given below
- Mercury Barometer
- Aneroid Barometer
Mercury Barometer
Mercury barometer has a glass tube which is closed at the top and open at the base. At the bottom part of the cylinder is a pool of mercury. The mercury sits in a round, shallow dish encompassing the cylindrical tube.
- This will change itself to coordinate with the air pressure over the dish.
- As the tension builds, it powers the mercury up the tube.
- This is set apart with a progression of estimations that track the number of atmospheres or bars.
Mercury Barometer
Aneroid Barometer
The aneroid barometer was developed by Lucien Vidi in 1884. It is a sealed metal chamber that expands and contracts as the atmospheric pressure in the environment changes.
- It is composed of fluid and made up of an aneroid capsule, a thin and flexible alloy metal box of beryllium and copper.
- To get better expansion and contraction of the levers as well as springs of the box, which developed due to the change in the atmospheric pressure outside the metal box as the box is sealed tightly.
Uses of Barometer
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Various applications of barometer are as follows:
- A barometer is used in the field of science to determine the weather conditions.
- The device is used in watches and smartphones.
- It is used for the measurement of altitude.
- Aircraft make use of aneroid barometers in the form of altimeters.
- GPS software also uses the barometer to determine the height of the device.
How to make a Barometer?
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A barometer is used to analyse atmospheric pressure. Low pressure indicates rainy weather, while high pressure indicates mild cool weather. You don't need an expert to study a barometer. You can prepare your own device to determine the weather.
Things you will need
Following are some of the instruments which are required in making a barometer:
- Permanent Marker
- Solid paper- Card like
- Straw
- Transparent Tape
- Rubber Band
- Jar
- Scissors
- Balloon
Procedure
Below are given a step-by-step process to make a well and good functional barometer
- Cut the top position of the balloon.
- Fix the cut part of the balloon with a rubber band over the jar by extending it out.
- A straw will be fixed over the balloon using the tape in such a way that one-third of it hangs over the edge.
- Draw three lines over the card at an equal space of around half a centimetre. Mark the lines as low, moderate, and high.
- The card must be taped at the backside of the jar, making the straw point towards moderate.
- Place the apparatus somewhere indoors on a flat surface.
This way, you can create a barometer. If the pressure difference between the inside and outside pressure is higher than the outside pressure, the balloon expands. Again, if the pressure difference is low, the balloon starts contracting.
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Things to Remember
- Mercury barometer is one of the oldest barometers invented by an Italian scientist in the year 1643.
- This measures air pressure and is designed especially for the monitoring of weather and their predictions.
- The barometer measures the atmospheric pressure in the unit bar or atm.
- The atmospheric pressure in vacuum areas is negligible.
- In a barometer, a rising barometer means the pressure is increasing, whereas falling indicates decreasing pressure.
- A meteorologist uses this information to determine whether a storm is coming or ending.
Sample Questions
Ques. How can you check whether the barometer has air or not? (1 mark)
Ans. The tube of the barometer rises or falls in the trough of mercury. If the height of the mercury changes in the tube, then we can say that it contains air.
Ques. Why to empty an oil container two holes are made? (2 marks)
Ans. This is because if there is only one hole in the tube, the pressure inside the tin will be less than the atmospheric pressure and the oil will not come out. That's why two holes are made to equal the inside pressure and the atmospheric pressure of the tin so that the oil would come out easily.
Ques. What does barometric pressure tell us? (2 marks)
Ans. It is the measurement of atmospheric pressure in the climate, explicitly the measurement of the weight applied via air particles at a given point on Earth. This additionally changes with the climate or rather, the climate changes with changes in barometric pressure.
Ques. How is a barometer used? (2 marks)
Ans. It is a scientific instrument used to quantify atmospheric pressure, known as barometric pressure. The environment is the layers of air folded over the Earth. That air has a weight and presses against all that it contacts as gravity pulls it to Earth and it is measured by a barometer.
Ques. What is the difference between a manometer and a barometer? (2 marks)
Ans. Barometer is designed to measure the atmospheric pressure, while a manometer can likewise be utilized to quantify the pressure which is lower than the weather. A manometer is a standard pressure instrument, worked for any characterized estimating range, conceivably up to 100 bar or more.
Ques. What are the advantages of the mercury barometer? (2 marks)
Ans. Some of the advantages of using barometer are given below
- Density is very high.
- Low vapour pressure.
- Rate of evaporation is not very high.
- It neither gets wet nor sticks to glass.
- Surface is opaque and shining.
Ques. What happens when air exerts pressure on our body? (2 marks)
Ans. The pressure applied via air on all bodies consistently in every direction is called air pressure. At the point when air moves at high rates, it makes a low pressure region. The air inside an inflatable applies pressure in every way, and makes it explode. Air opposes the movement of moving objects.
Ques. Why is mercury used in barometers? (2 marks)
Ans. Mercury is utilized in the barometer because its thickness is adequately high for a general short section to be obtained. and also because it has very small vapour pressure at ordinary temperature. High thickness downsizes the strain height to represent the same extent of tension in a container of more modest height.
Ques. What is the difference between barometer and manometer? (3 marks)
Ans. The difference between barometer and manometer are as follows:
| Barometer | Manometer |
|---|---|
| Barometer was established in 1643 by Evangelista Torricelli. | The manometer was developed in 1661 by Otto von Guericke |
| It is used in fitness app of smartphone and GPS chips for quicker locks and altitude data transfer. | It is used for measuring gas pressure in water pipelines. |
| The device depend upon low vapour pressure and a modest rate of evaporation. | This device have low costs and outstanding sensitivity and accuracy. |
Ques. What are the uses of barometer? (3 marks)
Ans. The uses of barometer are as follows:
- A barometer is used in the field of science to determine the weather conditions.
- The device is used in watches and smartphones.
- It is used for the measurement of altitude.
- Aircraft make use of aneroid barometers in the form of altimeters.
- GPS software also uses the barometer to determine the height of the device.
Ques. Why is mercury used in a barometer? (2 marks)
Ans. The barometric liquid in a barometer is mercury. When utilized as a measuring liquid in a barometer tube, mercury offers numerous benefits. The density of Mercury is high. This characteristic ensures that the height of the mercury in the barometer tube will change in a fairly acceptable manner in response to changes in pressure.
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| Class 11 Physics Study Guides | ||
|---|---|---|
| NCERT Solutions for Class 11 Physics | Topics for Comparison in Physics | Formulas in Physics |
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