Page 15 - Science Class 6 Times Publication

Some liquids like mercury do not wet the walls of vessels. In such
liquid, the middle part is raised up while the sides are depressed
down. Such meniscus is called convex meniscus.

Activity 1.6

Measure the volume of a piece of stone.

Take a measuring cylinder  lled
with water upto its half part.
Note down the volume of water.
You should observe the water
level by keeping eyes straight
to the lower meniscus in the
measuring cylinder. If the eyes
are above the surface of water,
the volume of water will be seen
more. Similarly, if the eyes are
below the water level the volume
will be seen less.

Now, tie a small piece of stone with a piece of thread and dip it into
the measuring cylinder .

What will you observe ?

The level of water in the measuring cylinder increases. Note down
the new volume in the cylinder. Hence,

Initial volume of water in the measuring cylinder (v ) = 50ml
1
Volume of the water after dipping the stone(v ) = 70ml
2
Therefore, volume of the stone (v) = v —v =70ml-50ml= 20ml
2 1
Measuring the volume of a gas

It is difcult to measure the exact volume of gases because the gases

are compressible. A measuring cylinder can also be used to measure
the volume of a gas.

Times' Crucial Science and Environment 11 Book 6