- 3 D SHAPE
Wondering how ?Come on!Let us perform the simple activity using available things at home.
- A plate of soap solution
- A glass bangle
- Three pieces of thread of equal lengths
- A pair of scissors
How do we do:
Take the bangle and tie one end of the thread to the bangle.Cut the excess length of the thread near the knot.Tie two more threads in similar way.Form a triangular frame work by tying the free ends of all the three threads.Now immerse the frame work completely in the soap solution.Gently lift the frame work out of the solution.Observe the THREE D shape formed by the triangular frame work out of SOAP FILM.The frame work can be made of metal wires for better results using soap solution with a little proportion of glycerin.
Link to the video can be found below
link to the vedio;https://youtu.be/8bfFH9n3-Ms
How do I do ?
Take the plate and add milk in it. Drop a pinch of each food coloring one by one on the surface of milk at the center.Next add a drop of soap solution gently on the surface using a cotton swab.Soap has started its magical art work on milk. Amazing but simple.
Soap molecules reduce the surface tension of water and milk and separates the molecules from each other increasing the distance them.
Want to know more? Soap breaks the fore of attraction between the molecules of milk.The force of attraction is termed as” COHESIVE FORCE”.This force accounts for the stretched elastic membrane like nature of the liquid surface.
What is surface tension?
Molecules of the same substance are called “LIKE MOLECULES”.There are only air molecules above the surface of milk or any liquid taken in a vessel…meaning no like molecules above the surface.This leads to stronger force of attraction (cohesive force) among the molecules on the surface.Hence the stretched skin like nature of the surface of liquids called”SURFACE TENSION”.
Water molecule is made of one oxygen atom and two smaller hydrogen atoms.The hydrogen atoms hold a slight positive charge.This makes water molecule polar.Hydrogen atoms of one water molecule attract oxygen atoms of other water molecules.Thus each water molecule is pulled by other water molecule from all directions.Since there are no like molecules on the surface,they have more force of pull from the molecules below and sideways.The net cohesive force aligns the water molecules closer together on the surface.These molecules give the skin like nature for the surface of the liquid.
Soap molecules also have two ends.One end of the soap molecules moves away from water molecules to the surface. This reduces the force of attraction of the water molecules on the surface thereby breaking the surface tension.
The link to the video :
Take a tumbler filled with water till the brim.Drop coins one by one slowly from the edge into the tumbler through the water. See whether water overflows or not.Surface of water just bulges out like a stretched rubber sheet and holds the coins as though in a bag of water.Guess why?
Few more activities to be followed based on the same concept… Keep guessing the reason.
We will find out the reason after a week!