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प्रश्न
Describe the construction and working of mercury barometer.
उत्तर
The instrument used to measure atmospheric pressure is called barometer. A mercury barometer, first designed by an Italian Physicist Torricelli, consists of a long glass tube (closed at one end, open at the other) filled with mercury and turned upside down into a container of mercury. This is done by closing the open end of the mercury filled tube with the thumb and then opening it after immersing it in to a trough of mercury. The barometer works by balancing the mercury in the glass tube against the outside air pressure.
If the air pressure increases, it pushes more of the mercury up into the tub and if the air pressure decreases, more of the mercury drains from the tube. As there is no air trapped in the space between mercury and the closed end, there is vacuum in that space. Vacuum cannot exert any pressure. So the level of mercury in the tube provides a precise measure of air pressure which is called atmospheric pressure. This type of instrument can be used in a lab or weather station.
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संबंधित प्रश्न
Match the following.
| Barometer | reduce friction |
| Increasing area of contact | Atmospheric pressure |
| Decreasing area of contact | cause of friction |
| Lubricants | increases friction |
| Irregular surface | decreases friction |
The instrument used to measure atmospheric pressure is ______.
Higher Order Thinking Skill.
How high does the mercury barometer stand on a day when atmospheric pressure is 98.6 kPa?
A mercury drop of radius 'R' is divided into 27 droplets of same size. The radius 'r' of each droplet is ______.
When a mercury drop of radius 'R', breaks into 'n' droplets of equal size, the radius 'r' of each droplet is ______.
Let 'R1' and 'R2' are radii of two mercury drops. A big mercury drop is formed from them under isothermal conditions. The radius of the resultant drop is ______.
______ is the instrument used to measure atmospheric pressure.
On each 1 m2 of surface, the force acting is ______.
The barometer works by balancing the Mercury in the glass tube along with the outside air pressure.
Match the following.
| Column I | Column II |
| a) Barometer | i) reduce friction |
| b) Increasing area of contact | ii) Atmospheric pressure |
| c) Decreasing area of contact | iii) cause of friction |
| d) Lubricants | iv) increases friction |
| e) Irregular surface | v) decreases friction |
