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Practical - Screw Guage

The document outlines an experiment to determine the diameter of a wire using a screw gauge, detailing the necessary apparatus, theory, and calculations involved. It includes instructions for measuring the diameter, recording observations, and calculating the mean diameter. Additionally, it lists precautions to ensure accurate readings and avoid errors.

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Rudra Banerjee
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31 views3 pages

Practical - Screw Guage

The document outlines an experiment to determine the diameter of a wire using a screw gauge, detailing the necessary apparatus, theory, and calculations involved. It includes instructions for measuring the diameter, recording observations, and calculating the mean diameter. Additionally, it lists precautions to ensure accurate readings and avoid errors.

Uploaded by

Rudra Banerjee
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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INDEX

S Date of Page
Name of experiment Signature
No. Experiment No.

01. 04.05.2023 To find the diameter of a cylindrical rod with


the help of vernier calipers.

02. To find the diameter of a wire by using screw


guage.
Experiment 02
Aim: To find the diameter of a wire by using screw guage.

Apparatus required:

 1 wire piece
 1 screw guage

Theory:

Pitch and least count of a screw guage:

The pitch of a screw guage is the linear distance moved by its screw on the main scale when the
circular scale is given one complete rotation, say p mm.

The least count of a screw guage is obtained by dividing the pitch (p) by the total number of
divisions on circular scale (N), i.e.,

p
L.C. = mm
N

Let us assume that while measuring the diameter, the main scale reading is a cm and the division
m on circular scale coincides with any division of the main scale. Then circular scale reading =
(m × L.C.) mm. Hence, total diameter, d = a + (m × L.C.) mm.

The entire experiment is repeated for two more times and two more readings of d2 and d3 are
taken. After that the average reading is taken as:

d 1+ d 2+ d 3
D= mm
3

If the screw guage is free from zero error, then the average reading gives the true diameter of the
wire.

Data:

Value of 1 smallest main scale division (or smallest division of the linear scale) (s) = _____ mm

Number of rotations given to the screw = _____

Distance moved on the main scale = _____ mm

Distance moved on the main scale


Pitch of the screw (p) = the screw ¿ = _____ mm
No . of rotations given¿

Total number of divisions on circular scale (N) = _____


Therefore,

p
L.C. = = _____ mm
N

Observation table

Circular Circular scale


No. of Main scale reading, Total diameter,
division reading,
obs. a (in mm) d = a + c (in mm)
coinciding, m c = m × L.C. (in mm)
01. d1 =
02. d2 =
03. d3 =

d 1+ d 2+ d 3
Mean diameter, D = mm = _____ mm
3

Conclusion:

Since the screw guage used is free from zero error, true diameter of the wire = _____ mm.

Precautions:

1. The readings using screw guage must be taken with proper care so as to avoid any parallax.

2. To avoid backlash error in the screw, the screw should be moved in the same direction.

3. We have to check for zero error in the screw guage, if any, before taking the readings.

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