Screw Gauge Experiments for Measuring Wire and Sheet Thickness

Screw Gauge Experiments for Measuring Wire and Sheet Thickness

Screw gauge experiments focus on measuring the diameter of wires and the thickness of sheets with precision. The document outlines step-by-step procedures for using a screw gauge, including determining the least count and zero error. It provides detailed observations and calculations for both wire and sheet measurements. Ideal for physics students and practical lab courses, this guide enhances understanding of measurement techniques and error analysis. It also includes methods for calculating volume using an irregular lamina, making it a comprehensive resource for practical applications in physics.

Key Points

  • Details procedures for measuring wire diameter using a screw gauge.
  • Explains the method for determining the thickness of a sheet with precision.
  • Includes calculations for zero error and least count of the screw gauge.
  • Describes how to measure the volume of an irregular lamina using area and thickness.
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EXPERIMENT 3
SCREW GAUGE - 1
AIM
To measure diameter of a given wire using a screw gauge and find its volume.
APPARATUS
Screw gauge, wire.
THEORY
1. If with the wire between plane faces A and B, the edge of the cap lies ahead of Nth
division of linear scale.
Then, linear scale reading (L.S.R.) = N
If nth division of circular scale lies over reference line.
Then, circular scale reading (C.S.R.) = n x (L.C.) (L.C. is least count of screw gauge)
Total reading (T.R) = L.S.R. + C.S.R. = N + n x (L.C.).
. .
DIAGRAM
. Screw gauge-measuring diameter (thickness) of the wire
PROCEDURE
1. Find the value of one linear scale division (L.S.D.).
2. Determine the pitch and the least count of the screw gauge and record it stepwise. . .
3. Bring the plane face B in contact with plane face A and find the zero error. Do it three
times and record them. If there is no zero error, then record 'zero error nil'.
4. Move the face B away from face A. Place the wire lengthwise over face A and move
.the face B towards face A using the ratchet head R. Stop when R turns (slips) without
moving the screw.
5. Note the number of divisions of the linear scale visible and uncovered by the edge of
the cap. The reading (N) is called linear scale reading (L.S.R.).
6. Note the number (n) of the division of the circular scale lying over reference line.
7. Repeat steps 5 and 6 after rotating the wire by 90° for measuring diameter in a
perpendicular direction.
8. Repeat steps 4, 5, 6 and 7 for five different positions separated equally throughout
the length of the wire. Record the observations in each set in a tabular form.
9. Find total reading and apply zero correction in each case.
10. Take mean of different values of diameter.
11. Measure the length of the wire by stretching it along a half metre scale. Keeping one
end of wire at a known mark , note the position of other end. Difference in position of
the two ends of the wire gives the length of the wire. Do it three times and record
them.
OBSERVATIONS
1. Determination of Least Count of the Screw Gauge
1L.S.D. = 1mm
Number of full rotations given to screw = 4
Distance moved by the screw = 4 mm
Hence, pitch=
4mm
4
=1mm
Number of divisions on circular scale = 100
Hence, least count =
1mm
100
= 0.01 mm = 0.001 cm.
2. Zero Error.
zero error (e) = mm
zero correction (c) = …….mm.
To measure the diameter
Serial No.
Linear Scale
Reading (N)
Observed circular
scale division
Corrected circular
Scale Reading (n
×V.C)
Total Reading
(T.R=l..S.R+C.S.
R)
CALCULATIONS
Mean diameter =……..mm
RESULT
The diameter of the given wire = ………….
PRECAUTIONS
1. To avoid undue pressure; the screw should always be rotated by ratchet R and not
by cap K.
2.The screw should move freely without friction.
3.The zero correction, with proper sign should be noted very carefully and added
algebraically.
4.For same set of observations, the screw should be moved in the same direction to
avoid back-lash error of the screw.
5.At each place, the diameter of the wire should be measured in two perpendicular
directions and then the mean of the two be taken.
6.Readings should be taken at least for five different places equally spaced along the
whole length of the wire.
7.Error due to parallax should be avoided.
SOURCES OF ERROR
1. The screw may have friction.
2. The screw gauge may have back-lash error.
3. Circular scale divisions may not be of equal size .
4. The wire may not be uniform.
EXPERIMENT 4
SCREW GAUGE -2
AIM
To measure thickness of a given. sheet using a screw gauge.
APPARATUS
Screw gauge, sheet (it must be rigid).
THEORY
1. If with the wire between plane faces A and B, the edge of the cap lies ahead of Nth
division of linear scale.
Then, linear scale reading (L.S.R.) = N
If nth division of circular scale lies over reference line.
Then, circular scale reading (C.S.R.) = n x (L.C.) (L.C. is least count of screw gauge)
Total reading (T.R) = L.S.R. + C.S.R. = N + n x (L.C.).
PROCEDURE
1. Find the value of one linear scale division (L.S.D.).
2. Determine the pitch and the least count of the screw gauge and record it stepwise. . .
3. Bring the plane face B in contact with plane face A and find the zero error. Do it three
times and record them. If there is no zero error, then record 'zero error nil'.
4. Move the face B away from face A. Place the sheet lengthwise over face A and move
.the face B towards face A using the ratchet head R. Stop when R turns (slips) without
moving the screw.
5. Note the number of divisions of the linear scale visible and uncovered by the edge of
the cap. The reading (N) is called linear scale reading (L.S.R.).
6. Note the number (n) of the division of the circular scale lying over reference line.
7. Repeat steps 4,5,6 for 5 different positions spread equally throughout the surface of
the sheet. Record observation in tabular form.
8. Find total reading and apply zero correction in each case.
OBSERVATIONS
1. Determination of Least Count of the Screw Gauge
1L.S.D. = 1mm , Number of full rotations given to screw = 4
Distance moved by the screw = 4 mm. Hence, pitch=
4mm
4
=1mm
Number of divisions on circular scale = 100
Hence, least count =
1mm
100
= 0.01 mm = 0.001 cm.
2. Zero Error.
zero error (e) = mm , zero correction (c) = …….mm.
To measure the thickness
Serial No.
Linea r Scale
Reading (N)
Observed circular
scale division
Corrected circular
Scale Reading (n
×V.C)
Total Reading
(T.R=l..S.R+C.S.
R)
CALCULATIONS
Mean thickness =……..mm
RESULT
The thickness of the given wire = ………..
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End of Document
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FAQs of Screw Gauge Experiments for Measuring Wire and Sheet Thickness

How do you measure the diameter of a wire using a screw gauge?
To measure the diameter of a wire using a screw gauge, first ensure the gauge is calibrated and check for zero error. Place the wire between the plane faces of the screw gauge and gently tighten until the ratchet slips, indicating contact. Record the linear scale reading and the circular scale reading to calculate the total diameter. Repeat the measurement in perpendicular directions to ensure accuracy and take the average of multiple readings for a reliable result.
What is the least count of a screw gauge and why is it important?
The least count of a screw gauge is the smallest measurement that can be accurately read using the device. It is calculated by dividing the pitch of the screw by the number of divisions on the circular scale. Knowing the least count is crucial for ensuring precise measurements, as it determines the smallest increment that can be measured. This understanding helps in minimizing errors during experiments and achieving accurate results.
What steps are involved in measuring the thickness of a sheet?
To measure the thickness of a sheet using a screw gauge, first calibrate the gauge and check for zero error. Position the sheet between the two faces of the gauge, ensuring it is flat and stable. Tighten the gauge until it grips the sheet without excessive force, then record the linear and circular scale readings. This process should be repeated at multiple points on the sheet to account for any variations in thickness, and the average of these readings should be calculated for accuracy.
How can the volume of an irregular lamina be calculated?
The volume of an irregular lamina can be calculated by first measuring its thickness using a screw gauge. Next, the area of the lamina is determined by tracing its outline on graph paper and counting the enclosed squares, treating half or more than half squares as full. The volume is then calculated by multiplying the area by the thickness. This method provides a practical approach to determining the volume of shapes that do not conform to standard geometric formulas.
What precautions should be taken when using a screw gauge?
When using a screw gauge, it is essential to avoid applying undue pressure; always use the ratchet to tighten the gauge. Ensure that the screw moves freely without friction, and take care to note any zero error accurately, applying the correct zero correction. To prevent backlash error, move the screw in the same direction for all measurements. Additionally, measure the diameter or thickness at multiple points to ensure consistency and accuracy in the readings.

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