MAKE YOUR OWN PRESSURE GAUGE

 

MAKE YOUR OWN PRESSURE GAUGE

 

                                                                                                                      Nikunja Bihari Sahu

 

         Water, like any other liquid, is capable of exerting pressure. Its pressing ability arises because of the distribution of its own weight. There are numerous applications of this principle in our daily life.  An under-water swimmer very well knows how strongly he is crushed by water as he plunges to more and more depths. Fishes living near the bottom of the sea have thin elongated bodies shaped due to the tremendous pressures of water from all sides. A deep sea diver needs a protective suit and helmet to stand up to the high pressure under water.  The walls of a dam, built across a river to stop and store water, are designed much thicker at the bottom than at the top to withstand the tremendous pressure of water.  Similarly, the reservoir in a public water supply system is placed at an elevated location to allow water to have sufficient pressure to flow to consumers located at lower grounds.

       There are three laws governing the pressure applied by water (or any liquid) at rest. These are:  Pressure increases with depth; Pressure remains same at any particular depth; Pressure is same from all directions at any point inside water. Let’s make a device to demonstrate the pressure applied by a liquid.   

What You Need

       Plywood sheet ( 6mm thickness)-12 inches x 6 inches),Wooden batten ( 1 inch x 1 inch x 8 inches), Iron nail, Transparent plastic tube ( diameter: ¼  inches that can be collected from a hardware shop), Cello tape, Plastic funnel, Balloon (large size) , Coloured liquid, Hammer, Paper cutter knife, Ink dropper and Bucket partially filled with water.

How You Make

        Fix the wooden batten on one side of the plywood sheet with nails so that the plywood sheet stands of its own. Fix the plastic tube on the opposite face of the plywood sheet in the shape of a ‘U’ with cello- tape. Introduce some coloured liquid into the limbs of the ‘U’ tube with an ink dropper. Normally, the level of coloured liquid remains at equal level in both the limbs of the ‘U’ tube. Attach the funnel to the free end of the ‘U’ tube with cello-tape air-tightly. Cut the balloon with the help of the knife and stretching the balloon sheet tightly over the face of the funnel, tape its edges to the brim of the funnel air tightly. So there you have your device ready! Such a device is commonly called the Manometer which is often used to measure the pressure of a liquid or gas.

 How You Do

        Dip the funnel into water taken in a bucket.  The water exerts pressure on the balloon sheet (attached to the funnel) which is communicated to the coloured liquid in the ‘U’ tube via the intermediate air mass.  As a result, the liquid (coloured liquid) level at the limb of the ‘U’ tube nearest to the funnel goes down and that at the other goes up – the difference of liquid column being the measure of the applied pressure.

            To verify the laws of pressure, plunge the funnel to more and more depths inside water taken in a bucket. The difference of liquid columns in both the limbs of the ‘U’ tube will increase indicating more pressure.  Next, move the funnel along a particular depth inside water touching all the points there.  Pressure will not change. Lastly, keeping the funnel fixed at any point, turn its face around to different directions. No change of pressure will be observed.

 

                                                                       Education Officer

                                                                                   Regional Science Centre

                                                                                    Pt. Jawaharlal Nehru Marg

                                                                                    Bhbaneswar-751013   

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