PHYSICS [2 Mark Question Answer]

SURFACE AREA INCREASES THE RATE OF EVAPORATION: On increasing the area of the surface, number of molecules escaping out from the surface increases.

For changing liquid into vapours heat is needed this heat is taken from the container or surroundings and temperature of container or body itself fall and cooling is produced.

APPLICATION OF THERMAL EXPANSION OF LIQUIDS: An important application is mercury thermometer or alcohol thermometer.
When the bulb of the thermometer is kept in contact with a hot body the mercury expands and the level of mercury rises in the capillary tube.

In summer when the temperature increases considerably the bridge made of metal expands and rollers slide to allow for expansion otherwise the bridge may break the pillar.

In summer due to considerable rise in temperature, the gaps allow for the expansion of rails, otherwise the rail will bend sideways.

Iron rims are made slightly smaller in diameter than the wooden wheel and on heating, wheel expands and can easily slip over the wooden wheel and on cooling the rim contracts and MAKES A TIGHT FIT OVER the wooden wheel.

On heating the ball expands and increases in size and cannot pass the ring when left on it. As the ball cools, it contracts, size becomes less than ring and passes the ring.

The increase in length of a rod on heating does not depend whether it is hollow or solid. If we heat two rods of the same metal and of the same length, but one hollow and the other solid , to the same rise in temperature, we find that both the rods expand to the same extent.

MATTER: Anything around us is a matter.
“Anything that has mass, occupies volume and can be felt by our senses.”
It is composed of molecules.

During boiling the heat energy supplied is used in increasing the energy of water molecule and hence the change of phase takes place. On recieving sufficient amount of energy it get converted into the gaseous state.