How is atmospheric pressure related to the height of a column of mercury in a mercury barometer?

How is atmospheric pressure related to the height of a column of mercury in a mercury barometer?

At sea level, a mercury column will rise a distance of 760 mm. This atmospheric pressure is reported as 760 mmHg (millimeters of mercury). At higher altitudes, the atmospheric pressure is decreased and so the column of mercury will not rise as high.

What is the value of atmospheric pressure in terms of mercury column?

approximately 14.7 psia
At sea level and at a temperature of 0° Celsius (C), the height of the mercury column is approximately 30 inches, or 76 centimeters. This represents a pressure of approximately 14.7 psia. The 30-inch column is used as a reference standard. Atmospheric pressure does not vary uniformly with altitude.

How does a mercury barometer measure atmospheric pressure?

A mercury barometer is an instrument used to measure atmospheric pressure in a certain location and has a vertical glass tube closed at the top sitting in an open mercury-filled basin at the bottom. Mercury in the tube adjusts until the weight of it balances the atmospheric force exerted on the reservoir.

Why is the unit of pressure for air given as atmosphere?

That pressure is called atmospheric pressure, or air pressure. It is the force exerted on a surface by the air above it as gravity pulls it to Earth. An atmosphere (atm) is a unit of measurement equal to the average air pressure at sea level at a temperature of 15 degrees Celsius (59 degrees Fahrenheit).

What is the height of mercury for one atmospheric pressure?

760 mm
Standard sea-level pressure, by definition, equals 760 mm (29.92 inches) of mercury, 14.70 pounds per square inch, 1,013.25 × 103 dynes per square centimetre, 1,013.25 millibars, one standard atmosphere, or 101.325 kilopascals.

Why is water not used in barometer?

water cannot be used as barometric liquid because it’s density is lower than Mercury . water’s density is 1000 gram per cubic meter. hence it requires a barometer whose height is around 11 meters.

What is the value of one atmospheric pressure?

approximately 14.7 pounds per square inch
One standard atmosphere, which is also referred to as one atmosphere, is equivalent to 101,325 pascals, or newtons of force per square metre (approximately 14.7 pounds per square inch).

Why is mercury used for pressure?

Mercury is commonly used in barometers because its high density means the height of the column can be a reasonable size to measure atmospheric pressure. A barometer using water, for instance, would need to be 13.6 times taller than a mercury barometer to obtain the same pressure difference.

What is considered low atmospheric pressure?

A barometric reading below 29.80 inHg is generally considered low, and low pressure is associated with warm air and rainstorms.

What is the basic principle of barometer?

A barometer is essentially a balance. The weight of the atmosphere is balanced by the weight of a much shorter mercury column. You can’t use an ordinary pan balance to weight the atmosphere (because air is pushing down on both sides).

What is normal air pressure in HG?

Know what represents reasonable barometer readings Normal is 29.9; range ~29.6 – 30.2 inches Hg (752-767 mm Hg)… at SEA LEVEL! Rarely (at sea level) do readings exceed 30.4 inches Hg (773 mm Hg)… except for occasional arctic highs in January. Rarely (at sea level) do readings fall below 29.5 inches Hg (749 mm Hg)…

How do you calculate atmospheric pressure?

Atmospheric pressure is the pressure caused by the mass of our gaseous atmosphere. It can be measured using mercury in the equation atmospheric pressure = density of mercury x acceleration due to gravity x height of column of mercury.

How tall is a column of mercury in the atmosphere?

Well, we know that 1 ⋅ atmosphere pressure will support a column of mercury that is 760 ⋅ mm high. And thus a mercury column, a mercury barometer, is an excellent means to monitor atmospheric pressure, or pressures LOWER than atmospheric pressure.

How to calculate the pressure of the mercury column?

P = ρ × h × g where ρ= density of mercury, h = height of column, g = acceleration due to gravity, For 1 atmosphere, ρ = 13.596 × 10-3Kg m-3 h = 0.76 m g = 9. 81 ms-2 Thus, 1atm.

How does atmospheric pressure affect the length of a column?

So column length is a good and visual gauge of the pressure. Of course, daily variations in atmospheric pressure will cause the length of the column to vary. Would the length of the column be the same at altitude?

And thus a mercury column, a mercury barometer, is an excellent means to monitor atmospheric pressure, or pressures LOWER than atmospheric pressure. Mind you, mercury has all but disappeared from laboratories and doctors’ surgeries in that (i) it is toxic; and (ii) if you spill the mercury it is very difficult to clean it up.