Page 40 - Physics

Physics for Secondary Schools

The vernier scale is shorter scale than the
main scale. 10 vernier divisions cover
9 main scale divisions. This is a length
of 0.9 cm. When this is divided into 10
equal intervals, the result is the difference
between the main scale division and the
vernier scale division. This is known as
Least Count.
1 cm
Main scale division = = 0.1 cm.
10 Figure 2.10: Measuring the inner diameter
using inside jaws
0.9 cm
Vernier scale division= = 0.09 cm.
10
Therefore,
least count of a vernier calliper

= (0.1 – 0.09) cm = 0.01 cm.

The vernier calliper has a set of jaws that
can be used to measure the length thickness,
and depth of objects as shown in Figure 2.9.

Figure 2.9: Measuring an external diametre
using the outside (lower) jaws Figure 2.11: Measuring depth using the
At the top of a vernier calliper are two inner vernier calliper
(upper) jaws that can be used to measure How to read a vernier calliper
the internal diametre of a hollow object,
shown in Figure 2.10. A stem that sticks out The following steps are taken when
from the right side of the calliper is called measuring length using a vernier calliper.
a depth gauge or the depth probe. It can be 1. Close the jaws of the vernier calliper
adjusted to measure a depth of an object, and look out for the zero mark (0 cm)
as shown in Figure 2.11. The screw clamp differences.
visible on top of the calliper is tightened 2. Place the object to be measured between
to secure the objects being measured so the jaws.
that the reading does not change while 3. Slide the vernier along the main scale
measuring. until it just touches the end of the object.

34
Student’s Book Form One

Physics Form 1 Final.indd 34 16/10/2024 20:55