Page 39 - Physics

Measurement

different methods for reading measurements, such as ruled scales or electronic displays.
The accuracy of measurements taken with callipers depends signifi cantly on the skills
of the user and the proper application of the tool against the object being measured.

Vernier calliper: A vernier calliper is an instrument used to measure small lengths with a
greater degree of accuracy than a metre rule. It is used to measure objects to the nearest
hundredth of a centimetre, which means its accuracy is 0.01 cm. A vernier calliper has a
fi xed scale and a vernier scale. The fi xed scale is also known as the main scale. The vernier
scale slides along the fi xed scale hence readings are taken from both scales. The fi xed
scale gives readings in centimetres and millimetres. The vernier scale gives readings in the
hundredth of a centimetre. That is, the vernier scale gives the second decimal place of the
measured value. Figure 2.7 show parts of a vernier calliper.

Inside jaws Vernier scale
Main scale

Main scale Depth probe
Vernier scale

Outside jaws Figure 2.7: Parts of a vernier calliper

Digital calliper: As with the normal vernier calliper, the digital callipers also consist of
mechanical parts like external jaws, internal jaws, stem, and screw lock and we cannot fi nd
the main scale, vernier scale because this is a digital vernier so there will be no use and
necessity of main scale and vernier scale; instead, we can see the reference scale on the
digital vernier calliper. This kind of calliper is automatic, so it certainly uses electrical and
electronic parts for its working, therefore, the components that respond to the digital system
are capacitance Sensors, LCD, copper plates, chips and battery as shown in Figure 2.8.

Internal Metric/Inch Locking
Metric/Inch
Locking
Jaws Button Screw
Jaws
Button
Screw
Scale
LCD display Scale
LCD display

Power
Power Zero setting Depth measuring
Zero setting
Depth measuring
ON/OFF blade
ON/OFF
blade
External jaws
External jaws
Figure 2.8: Parts of a digital calliper
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