What is VERNIER CALLIPERS ? How to use it?
This instrument is used to measure accurately up to 0.1mm.
It was designed by French Mathematician Pierre Vernier and after his name it is named Vernier Callipers.
It works on the principle of using alignment of line segments displaced by a small amount to make fine measurements.
In Vernier Callipers the jaws open to a maximum of 150mm to 2000mm.
It can commonly measures upto 6 inches.
It can be used for three types of measurements outside distance, inside distance and depth.
CONSTRUCTION:
The main parts of Vernier Callipers are:
1)Main Scale
2)Vernier Scale
3)Jaws:
Outside jaw are used to take external measures of an object.
Inside jaw are used to take internal measures of objects.
4)Strip(Depth probe):
It is used to measure the depth of objects.
How to find the ZERO ERROR of Vernier Callipers?
If the zero of main scale coincides with zero of Vernier Scale when the jaws are brought in contact with each other,then there is no zero error in the instrument.
But if the zero mark of the Vernier Scale does not coincide with zero of the main scale ,then it gives rise to an error called zero error.
POSITIVE ZERO ERROR:
When the zero mark of Vernier Scale lies towards the right side of the zero of the main scale ,when the jaws are made to touch each other.In this case the zero error is said to be positive zero error.
To get the reading the zero error is to be subtracted from the observed value.
NEGATIVE ZERO ERROR:
When the zero mark of the Vernier Scale lies towards the left side of the zero of the main scale when the jaws are in contact.
In this case the zero error is said to be negative zero error.
LEAST COUNT OF VERNIER CALLIPERS(VERNIER CONSTANT):
=Smallest division on main scale/Total number of divisions on Vernier Scale
=1/10
=0.1mm
=0.01cm
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