10th Class Physics - Question & Answers - Heat

10th Class Physical Science - Question Bank

Equal amounts of water are kept in a
cup and in a dish. Which will evaporate
faster? Why?

The rate of evaporation increases with

increasing in surface area. The surface

area of water in dish is more than the

surface area of water in cup. So Water in

dish will evaporate quickly

Suggest an experiment to prove that
the rate of evaporation of a liquid
depends on its surface area and
vapour already present in surrounding
area.

Experiment to prove that Evaporation

depends upon the surface area of the

liquid:

Take 5ml of spirit in a small plate And take

5ml of spirit in another big plate (without

lid). Keep them some time.

Observation : The spirit in the big dish

that disappears quickly, where we find

some spirit in the other dish which is

small. This means that Evaporation

depends upon the surface area of the

liquid. If surface area increases the rate of

evaporation also increases.

Experiment to prove that Evaporation

depends upon the vapour already present

in surrounding area:

Take 5ml of spirit in two small cups. Put

one cup in the A.C. room and put another

in the normal room. Measure the time

taken for disappear the spirit from the

cups.

Observation: The spirit in the normal

room disappears quickly.This means that

the rate of evaporation depends upon the

vapour already present in surrounding

area. If the vapour in atmosphere

increases then the rate of evaporation

decreases.