To study the aneroid barometer and determine the barometric pressure

Apparatus:-

Aneroid barometer

 Barometer:-

A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. It can measure the pressure exerted by the atmosphere by using water, air, or mercury. Pressure tendency can forecast short term changes in the weather. Numerous measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems, and frontal boundaries.

Aneroid Barometer:-

An aneroid barometer, invented by the French 19th century engineer and inventor Lucien Vidie, uses a small, flexible metal box called an aneroid cell. This aneroid capsule (cell) is made from an alloy of beryllium and copper. The evacuated capsule (or usually more capsules) is prevented from collapsing by a strong spring. Small changes in external air pressure cause the cell to expand or contract. This expansion and contraction drives mechanical levers such that the tiny movements of the capsule are amplified and displayed on the face of the aneroid barometer. Many models include a manually set needle which is used to mark the current measurement so a change can be seen. In addition,

the mechanism is made deliberately "stiff" so that tapping the barometer reveals whether the pressure is rising or falling as the pointer moves.

How it works:-

The aneroid barometer is operated by a metal cell containing only a very small amount of air, or a series of such cells joined together. Increased air pressure causes the sides of the cell or cells to come closer together. One side is fixed to the base of the instrument while the other is connected by means of a system of levers and pulleys to a rotating pointer that moves over a scale on the face of the instrument. This pointer is usually black.

The aneroid barometer (above) consists of a closed sealed capsule with flexible sides. Any change in pressure alters the thickness of the capsule.

Levers magnify these changes, causing a pointer to move on a dial, or numbers to change on a digital read-out device.

 

Advantages of Aneroid Barometer:-

• Aneroid barometers have a mechanical adjustment for altitude that allows the equivalent sea level pressure to be read directly and without further adjustment if the instrument is not moved to a different altitude.
• Easy to carry around.
• It is light-weight.
• Having no liquid.