My Science School

Warm the base of a candle and stick it to the bottom of a small bowl. Pour water into the bowl till the water reaches the rim of the candle. Light the candle. It will burn and the flame will form a crater in the candle.

The base of the flame will sink below the surface level of the water, but the water will be prevented from extinguishing the flame by the thin wall of wax that is left standing all around it.

How does the wall form?

The water takes up so much heat that the outer layer of the candle does not reach melting point. As a result, the wax there cannot evaporate and burn. It remains like a wall around the flame.

 

Picture Credit : Google

Immerse the egg in a bowl of water. If the egg lies horizontally on the bottom of the vessel containing the water the egg is probably fresh; if the egg stands on its pointed end, the egg may be several days old.

What is the basis for testing of freshness of eggs in this way?

Eggs contain tiny pores invisible to the naked eye, through which air can enter or leave the egg. The air in the egg is contained in the air cell situated at the broader end of the egg.

Due to the gradual evaporation of water from the egg after it has been laid, the air cell becomes larger as the days pass. This makes the broader end lighter than the rest of the egg, so if an egg that is several days old is placed in water, the broader side will float upward causing the egg to stand on its pointed end.

 

Picture Credit : Google