PHYSICS DEMONSTRATION
'Balancing Cutlery'
Aim:To demonstrate the centre of mass of an object.
Materials:Fork,spoon,glass half filled with water and toothpick.
Procedure:
1)First,hook the fork and spoon together by putting the two outside tines of the fork over the back of the spoon to form a sort of boomerang shape.
2)Place the toothpick between the centre prongs of the fork such that it also touches the spoon.
3)Position the resulting arrangement on the edge of the glass half filled with water such that the two handle ends point back towards the glass.
4)Balance the arrangement by moving the toothpick to the best spot on the rim of the glass.
Observation:The fork and spoon arrangement is balanced on the rim of the glass with the support of a toothpick.
Conclusion:The centre of mass of the fork and spoon lies in between them.The toothpick is placed there for the support to hold up and the centre of mass rests on the rim of the glass.Since the glass pushes the arrangement up with the exact force gravity pulls it down,it neither falls nor rises.Hence,all forces are in balance.
CHEMISTRY DEMONSTRATION
'Tyndall Effect'
Aim:To demonstrate the Tyndall Effect in a colloid and in a suspension.
Materials:Two beakers containing water,milk,garden mud,laser and dropper
Procedure:a)Colloid
1)Take a beaker filled with water and add a few drops of milk with the help of a dropper.
2)Shine the laser through the beaker.
b)Tap water
1)Take a beaker filled with water and shine the laser through it.
c)Suspension
1)Take a beaker filled with water and add some garden mud in it.
2)Shine the laser through the beaker before the mud settles down.
Observation:a)The laser beam is seen in the beaker.
2)The laser beam is not seen in the beaker.
c)The laser beam is seen in the beaker until the mud settles down.
Conclusion:a)The Tyndall Effect is seen in the milk and water mixture as milk is a colloid.Hence the milk particles are large enough to scatter the light and make its path visible through the liquid.
b)The Tyndall Effect is not seen in the water as it is not a colloid and hence the particles are too small to scatter the light.
c)The Tyndall Effect is seen in the muddy water as it is a suspension wherein the particles are large enough to scatter the light before they settle down.
BIOLOGY DEMONSTRATION
'Test for Vitamin C'
Aim:To test the presence of Vitamin C in orange juice and lemon juice.
Materials:Orange juice,lemon juice,test tubes,dropper,iodine solution and starch solution(dissolving 1 spoon of corn flour in warm water and cooling)
Procedure:a)Orange juice
1)Take some starch solution in a test tube and add a few drops of iodine solution to it.
2)Add a few drops of the orange juice.
b)Lemon juice
1)Take some starch solution in a test tube and add a few drops of iodine solution to it.
2)Add a few drops of the lemon juice.
Observation:a)When the iodine solution is added to the starch solution,it turns blue -black.When the orange juice is added to it.the colour changes to light brown.
b)When the iodine solution is added to the starch solution,it turns blue -black.When the lemon juice is added to it.the colour changes to light brown.
Conclusion:In both the cases,when the orange or lemon juice is added to the solution,the colour changes to light brown showing the presence of vitamin C in the juice.This happens because iodine is a very powerful oxidant which in a mixture of different substances,first reacts with the molecules that are easier to break down.In this case,it is the vitamin C in the juice which is an anti-oxidant.
MY EXPERIENCE
These were my first demonstrations conducted in the college.I learnt a lot of new things while preparing for the demonstrations.
'Balancing Cutlery'
Aim:To demonstrate the centre of mass of an object.
Materials:Fork,spoon,glass half filled with water and toothpick.
Procedure:
1)First,hook the fork and spoon together by putting the two outside tines of the fork over the back of the spoon to form a sort of boomerang shape.
2)Place the toothpick between the centre prongs of the fork such that it also touches the spoon.
3)Position the resulting arrangement on the edge of the glass half filled with water such that the two handle ends point back towards the glass.
4)Balance the arrangement by moving the toothpick to the best spot on the rim of the glass.
Observation:The fork and spoon arrangement is balanced on the rim of the glass with the support of a toothpick.
Conclusion:The centre of mass of the fork and spoon lies in between them.The toothpick is placed there for the support to hold up and the centre of mass rests on the rim of the glass.Since the glass pushes the arrangement up with the exact force gravity pulls it down,it neither falls nor rises.Hence,all forces are in balance.
CHEMISTRY DEMONSTRATION
'Tyndall Effect'
Aim:To demonstrate the Tyndall Effect in a colloid and in a suspension.
Materials:Two beakers containing water,milk,garden mud,laser and dropper
Procedure:a)Colloid
1)Take a beaker filled with water and add a few drops of milk with the help of a dropper.
2)Shine the laser through the beaker.
b)Tap water
1)Take a beaker filled with water and shine the laser through it.
c)Suspension
1)Take a beaker filled with water and add some garden mud in it.
2)Shine the laser through the beaker before the mud settles down.
Observation:a)The laser beam is seen in the beaker.
2)The laser beam is not seen in the beaker.
c)The laser beam is seen in the beaker until the mud settles down.
Conclusion:a)The Tyndall Effect is seen in the milk and water mixture as milk is a colloid.Hence the milk particles are large enough to scatter the light and make its path visible through the liquid.
b)The Tyndall Effect is not seen in the water as it is not a colloid and hence the particles are too small to scatter the light.
c)The Tyndall Effect is seen in the muddy water as it is a suspension wherein the particles are large enough to scatter the light before they settle down.
BIOLOGY DEMONSTRATION
'Test for Vitamin C'
Aim:To test the presence of Vitamin C in orange juice and lemon juice.
Materials:Orange juice,lemon juice,test tubes,dropper,iodine solution and starch solution(dissolving 1 spoon of corn flour in warm water and cooling)
Procedure:a)Orange juice
1)Take some starch solution in a test tube and add a few drops of iodine solution to it.
2)Add a few drops of the orange juice.
b)Lemon juice
1)Take some starch solution in a test tube and add a few drops of iodine solution to it.
2)Add a few drops of the lemon juice.
Observation:a)When the iodine solution is added to the starch solution,it turns blue -black.When the orange juice is added to it.the colour changes to light brown.
b)When the iodine solution is added to the starch solution,it turns blue -black.When the lemon juice is added to it.the colour changes to light brown.
Conclusion:In both the cases,when the orange or lemon juice is added to the solution,the colour changes to light brown showing the presence of vitamin C in the juice.This happens because iodine is a very powerful oxidant which in a mixture of different substances,first reacts with the molecules that are easier to break down.In this case,it is the vitamin C in the juice which is an anti-oxidant.
MY EXPERIENCE
These were my first demonstrations conducted in the college.I learnt a lot of new things while preparing for the demonstrations.
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