# How is pressure measured by using a mercury barometer?

## How is pressure measured by using a mercury barometer?

The barometer works by balancing the weight of mercury in the glass tube against the atmospheric pressure, much like a set of scales. If the weight of mercury is less than the atmospheric pressure, the mercury level in the glass tube rises (high pressure).

### What does the mercury barometer measure?

mercury barometer tool that determines atmospheric pressure by measuring how much mercury moves in a glass tube.

#### How does mercury barometer use to measure the column of the mercury?

In the mercury barometer, atmospheric pressure balances a column of mercury, the height of which can be precisely measured. To increase their accuracy, mercury barometers are often corrected for ambient temperature and the local value of gravity.

What is the use of mercury barometer?

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.

Why do we use mercury to measure 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.

## How does mercury barometer and aneroid barometer?

Photo: A Torricellian barometer (sometimes called a mercury barometer) is an inverted (upside-down) glass tube standing in a bath of mercury. Air pressure pushes down on the surface of the mercury, making some rise up the tube. The greater the air pressure, the higher the mercury rises.

### Why is mercury used as barometric liquid give three reasons?

(i) The density of mercury is greater than that of all the liquids, so only 0.76m height of mercury column is needed to balance the normal atmospheric pressure. (ii) The mercury neither wets nor sticks to the glass tube therefore it gives the correct reading.

#### How does a mercury barometer work?

How does a barometer work? Simply put, a barometer acts like a balance that ‘balances’ the weight of the atmosphere (or air around you) against the weight of a mercury column. If the air pressure is high, the mercury will rise. At low air pressure, the mercury goes down.

How do you measure atmospheric pressure with mercury barometer?

Here, then, are the steps to be done in using the barometer to measure atmospheric pressure: Lightly tap the barometer so that the height of the meniscus is neither too large or too small. Use the Zero Adjusting Knob so that the top of the Mercury Reservoir is just touching the tip of the Zeroing Peg.

What is a barometer and what does it measure?

A barometer is a scientific instrument used to measure atmospheric pressure, also called barometric pressure. The atmosphere is the layers of air wrapped around the Earth. That air has a weight and presses against everything it touches as gravity pulls it to Earth. Barometers measure this pressure.

## How tall is the vacuum in a mercury barometer?

Some of the mercury flows from the tube into the reservoir, creating a vacuum at the top of the closed end of the tube. The tube is generally about 3 feet (0.9 meters) tall and includes markings at regular intervals, usually in inches or millimeters, that are used to quantify changes in pressure.

### Is the mercury barometer calibrated for 0 O C?

The barometer is calibrated for 0 o C. For different temperatures a correction must be applied to compensate for the different expansions of the housing and the mercury. The following table shows the correction, in mm, that should be subtracted from the reading of atmospheric pressure: