Question

What is an Aneroid barometer? Draw a neat labelled diagram to explain its construction and working.

Answer 1

Hint: There are two types of barometers. They are Aneroid barometers and Mercury barometers. These are the devices that are used to measure the atmospheric pressure. An Aneroid barometer belongs to a non-liquid barometer and Mercury barometer belongs to liquid barometer.

Complete answer:
Aneroid barometer: The device that is used to measure the atmospheric pressure is called aneroid barometers. Altitude or height can also be measured using the barometers as the pressure of the atmosphere changes with the change in the distance level. The pressure that is measured by the barometer is called Barometric pressure.

The diagram of the Aneroid barometer is given.

Construction: The above diagram shows the main parts of the aneroid barometer.
• It has a metallic box B that is partially evacuated.
• The top D is kind of springy and is corrugated in the form of a diaphragm.
• A thin rod L is placed in the middle of the diaphragm that is toothed at the upper end.
• A wheel is placed near to the diaphragm; the teeth of the diaphragm are correctly fitted into the teeth of the wheel.
• A pointer P is made to slide with the circular scale.
• The circular scale is calibrated with the barometer to read the atmospheric pressure.

Additional information:
Working of the aneroid barometer:
• The diaphragm D gets pressed, when the pressure of the atmosphere increases. Rod L will get depressed. When this happens the wheel S rotates in the clockwise direction and the point P will move to the right of the circular scale.
• The diaphragm D will get bulged when the rod L gets moved up and the wheel will be rotating in the anti-clockwise side. Due to this the pointer will move to the right. This happens when the atmospheric pressure decreases.

Note:
• It is important to remember about the types of the barometers. One is a mercury barometer and another one is an aneroid barometer.
• In an aneroid barometer, the pressure will be measured by the metal expansion and in the mercury barometer the mercury’s height must be adjusted to measure the pressure.
• Mercury barometer has a simple mechanism and it is relatively accurate whereas an aneroid barometer needs a complex mechanism.