Object : To establish the relation between the loss in weight of a solid fully immersed in (i) Tap water (ii) Strongly salty water , with the weight of water displaced by it by taking two different solid.
Apparatus : Spring balance , steel or brass Bob , graduated measuring cylinder , thread , water , clamp stand and a Eureka can ( a glass or metallic container with a spout.
Theory : Archimede's principle states that when an object is immersed wholly or partially in a liquid , it experiences an upward force which is equal to the weight of the liquid displaced by it.
Apparent loss of weight of solid in water = weight of water displaced by the solid.
Diagram :
Observation :
Weight of the bob ( made of steel or brass ) in air , W1 = ........ gmt.
Weight of the bob when dipped in water , W2 = ....... gwt
Apparent loss of weight of bob in water = W1 - W2 = ...... gwt
Density of water at 4°C ( From tables ) = 1 g/cm3
Volume of water collected in the measuring cylinder , V = ....... Cm3
Calculations : Apparent loss of weight of bob in water = volume of water collected in measuring cylinder.
W1-W2 = V
Result : Since apparent loss of weight of bob in water is equal to the volume of water collected in measuring cylinder , the Archimede's principle is verified.
Precautions:
1. The spring balances should not have any zero error.
2. The measuring cylinder should be dry.
3. There should not be any leakage of water from the Eureka can.
4. The spring balances should be suspended vertically.
5. The Bob should be completely immersed in water.
6. The graduations marks on the measuring cylinder and on the spring balance should be evenly spaced.
Sources of Error :
1. The impurities present in water may alter its density.
2. The steel or brass Bob should not be porous.
3. The thread used in the experiment may also absorb some water.