How to Make a Mercury Barometer

You are a science student and have been asked by your teacher to make a project for science. If you intend to be a scientist or have a good aptitude towards science then it may not be a tough ask for you. However, if you are one of the back benchers then this assignment will perhaps have you all at sea. If you cannot think of a decent project for science but at the same time want to make a real good one then the best thing to do is try making a simple Mercury Barometer. Basically, a barometer is an instrument that is used for the measurement of atmospheric pressure. Hence a simple mercury barometer uses the height of mercury column to measure atmospheric pressure which is measured in cm Hg. Following few simple directions you can make a simple mercury barometer.

Instructions

  • 1

    Filling glass tube with mercury

    Take a thick-walled glass tube with one end closed and fill it with mercury. Try filling it to the brim such that there are least chances of having any air trapped in the tube.

  • 2

    Filling a dish with mercury

    Now take a small dish made up of glass and fill it with mercury. While you are filling it with mercury make sure that you don’t let t over flow as mercury is quite an expensive item.

  • 3

    Create Vacuum above mercury

    Now pick up the glass tube that you earlier filled with mercury. In order to ensure that there are no bubbles of air inside the tube fill more mercury with help of a dropper. You may also connect a vacuum pump for drawing mercury into the tube and keeping a vacuum at the top of the barometer.

  • 4

    Inverting Glass Tube on Mercury Dish

    Place your finger at the top of the glass tube and invert it over the open mercury dish. After that, slowly remove your finger from the open end of the glass tube.

  • 5

    Making Observations

    As you will remove the finger, it will be observed that the level of mercury in the glass tube begins to fall. However, at one point it will stop when there will be atmospheric pressure acting on the surface of mercury in dish.

  • 6

    Measuring Atmospheric Pressure

    Upon measuring with a meter rule, the height of the mercury column in the glass tube will be 760 mm which is standard atmospheric pressure.

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