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The basic principle of barometer is Torricelli's experiment. Imagine that you fill a tube of one metre length (100cm) with mercury up to the brim. Then close the mouth of the tube with your thumb and invert the tube and place it in a cistern of mercury with its end immersed in the mercury say some 4 cm. Now you remove your thumb. Mercury would come down but it stops at one level to our astonishment. This level would be some 20 cm from the closed end of the tube. So there will be almost 76cm column of mercury in the tube. Why is it so? As mercury comes down the space left vacant will not be having any air molecule and so it is almost vacuum. This is named as Torricelli's vacuum. Now the air outside in the atmosphere would exert a pressure and wants to push the mercury towards this vacuum place. But the weight of the mercury column (76cm) will balance this pressure. Hence we say the atmospheric pressure will be 76 cm of mercury. This is how we have mercury scale for measuring the pressure. Usually pressure is defined as the force per unit area. Hence the unit will be N/m2 or pascal. But we give pressure only in cm or mm of mercury. The reason is explained properly. Same technique is applied in Fortin's barometer and vernier arrangement is made to measure the pressure so accurately.
What else can I help you with?
What two units are commonly used to measure air pressure?
Probably a mercury barometer and a aneroid barometer. -adrian
Why would a water barometer have to be 13.6 times taller than a mercury barometer?
A barometer using water,would need to be 13.6 times taller than a mercury barometer to obtain the same pressure difference. This is because mercury is 13.6 times more dense than water.
What does a rising barometer tell you?
Mercury in the tube adjusts until the weight of the mercury column balances the atmospheric force exerted on the reservoir. High atmospheric pressure places more force on the reservoir, forcing mercury higher in the column.
What is the difference between how air pressure is indicated in a mercury barometer and an aneroid barometer?
Usually no difference at all. They can both move a pointer around a circular scale. The scale can be calibrated in both Inches of Mercury (InHg) or Millbars (Mb). An aneroid system can lend itself more easily to a digital display.
Why are aneroid barometers often more practical than mercury barometers?
The aneroid barometer is more durable and compact, and much easier to read. The only particular advantage of a mercury barometer is that it's a direct measurement -- there's no calibration involved. If you can measure the height of the column above the pool and you know the density of mercury, you have the pressure.
What are the uses of a Mercury barometer?
A Mercury barometer is used to measure atmospheric pressure.
What deos a barometer measure?
A barometer is used to measure air pressure. It measures the atmospheric pressure using air, mercury, or water and will be shown as inches of mercury or millibars.
What do mercury barometer measure?
It measure the Atmospheric Pressure.
Which statement accurately describes a difference between a mercury barometer and an aneroid barometer?
One statement to accurately describe a difference between a mercury barometer and an aneroid barometer is that a mercury barometer is a closed tube containing mercury. An aneroid barometer is a closed, flexible container of gas.
What is the device use to measure air pressure called?
The device used to measure air pressure is called a barometer. It can be either an aneroid barometer or a mercury barometer, both of which are commonly used to measure atmospheric pressure.
What a barometer with Mercury?
barometers with mercury measure air pressure. when the air pressure is high the mercury rises
Torricelli invented a device for measuring air pressure called a(n)?
Torricelli invented a device for measuring air pressure called a mercury barometer. It consists of a glass tube filled with mercury placed in a dish of mercury. The height of the mercury in the tube changes with variations in atmospheric pressure.
What two units are commonly used to measure air pressure?
Probably a mercury barometer and a aneroid barometer. -adrian
What measures a barometer with Mercury?
A barometer that uses mercury measures air pressure by monitoring the height of the mercury column in a tube. As air pressure changes, the mercury level rises or lowers in response. This instrument is called a mercury barometer.
What instutment would you use to measure air preesure?
a barometer... and it is invented by torricelli..
What does a mercury barometer measures?
Barometers are used to measure pressure.
What is a mercury barometer used for?
Mercury barometer is used for measuring atmospheric pressure. Because atmospheric pressure changes with distance above or below sea level, a barometer can also be used to measure altitude.
