Question

Make a lactometer with ballpoint refill. What would you do to make the refill stand vertically straight?

Answer 1

Hint: In the above mentioned question we will get to know about what is a lactometer and the principle on which it works i.e. the Archimedes principle. And also we will get to know about the steps to make a lactometer with a ball point.

Complete step by step solution:
Lactometer is a small glass instrument that is used to test the purity of the milk. It works on the principle of specific gravity of milk (Archimedes Principle). It measures the relative density of milk with respect to water. If the specific gravity of a sample of milk is within the approved ranges, the milk is pure. If it is not, then there is some adulteration.
Archimedes Principle :The Archimedes theory is concerned with the forces exerted on an object by the fluids that surround it. The net weight of an object immersed in a fluid is reduced by this applied force. This physical law of buoyancy also assists in our understanding of how ships float in water. Archimedes’ principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether partially or fully submerged, is equal to the weight of the fluid that the body displaces and acts in the upward direction at the centre of mass of the displaced fluid.
TO make a lactometer with ballpoint refill, follow the given steps :
1. Take an empty ball pen refill with a metal point at the bottom.
2. Take a boiling tube and fill it with water.
3. Put the refill in the water with a metallic point.
4. To make the refill stand in water, insert a small eraser piece in the refill at the centre.
5. Mark the point with a marker up to which the refill is above the water.
6. Now, empty the boiling tube with water and fill it with milk.
7. Again put the refill in milk and mark the point which shows the part which is above the surface of milk.
8. Further we can add milk water mixture in the boiling tube and repeat the same step 8.
9. We can now compare and test whether water is added to milk or not.

Note:
The specific gravity of milk does not give a conclusive indication of its composition since milk contains a variety of substances that are either heavier or lighter than water. Additional tests for fat content are necessary to determine overall composition. The instrument is graduated into a hundred parts.