It is commonly observed during the rainy season that
water falling on roads and streets dissapears after a few hours. Similary, in
summer, wet clothes dry up very soon. Do you know where the water goes? This
water got converted into vapor is called evaporation. Let me explain.
How does evaporation take place? Every substance is
made up of very small particles called molecules. These molecules are held
together by strong forces of attrition called cohesive forces. These forces are
opposed by the repulsive forces due to the motion of molecules. As long as the
cohesive forces are far greater than the repulsive force, the substance remains
in the solid state. When the substance is heated up, it absorbs heat energy which the molecules
area set up in rapid motion.
The motion
starts counterbalancing the cohesive
force, matter changes from solid to liquid state. If the liquid is still
heated, the molecules still move
fast. When the force exceed
the cohesive force, the molecules of the liquid become free and escape into the
air. It is how the liquid is converted into vapor. The liberation of the molecules from the liquid surface to the air is called
evaporation.
Oh I almost forgot. This explains the drying up
process of clothes. If the wet clothes are put under the sun, they dry up
faster because of the rate of evaporation increases with the rise in temperature.
It takes place more rapidly when the air is dery. That is why the clothes dry up more quickly on a dry than on a damp cloudy day.
Hmm.. Do you understand? Not yet?
Okay, how about going to the library to find more information about
“evaporation” and good luck.
Mawaddatun Niswah, 20:56 08/10/12
Tidak ada komentar:
Posting Komentar