Скачать или смотреть Familiarization with Vernier Calipers and Screw Gauge by measuring various samples (In Bangla)

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Course Title: Physics Lab I
Course Code: PHY 102

Experiment No.:01
Name of the Experiment:
Familiarization with Vernier Calipers and Screw Gauge by measuring various samples

Objectives of the Experiment:
• To know the use of the Vernier Calipers and Screw Gauge.
• To measure the length, width and height of the given rectangular block and then measuring the volume of the sample
• To measure the diameter of a small spherical body and then measuring volume of the sample.
Theory:

Vernier Calipers:

A Vernier calipers is a device used to measure the distance between two opposing sides of an object. It can be as simple as a compass with inward or outward-facing points. First the tips of the calipers are adjusted to fit across the points to be measured and the calipers is then removed and the distance between the tips is measured using a ruler. The modern Vernier calipers was invented by Joseph R. Brown in 1851. It was the first practical tool for exact measurements that could be sold at an affordable price to ordinary machinists. The Vernier Calipers consists of a main scale fitted with a jaw at one end. Another jaw, containing the Vernier scale, moves over the main scale. When the two jaws are in contact, the zero of the main scale and the zero of the Vernier scale should coincide. If both the zeros do not coincide, there will be a positive or negative zero error.

Screw Gauge:
The screw gauge is an instrument used for measuring accurately the diameter of a thin wire or the thickness of a sheet of metal. It consists of a U-shaped frame fitted with a screwed spindle which is attached to a thimble.

Apparatus:

Vernier calipers.
A small rectangular metallic block
Screw Gauge
Lead shot

Experimental Procedures:

We'll first determine the Vernier constant (VC), which is the least count (L.C) of the Verniercaliper and record it stepwise as in the equation, L.C = 1 MSD - 1 VSD.
Now, bring the movable jaw in close contact with the fixed jaw and find the zero error. Do this three times and record the values. If there is no zero error, then record 'zero error nil'.
Open the jaws of the Vernier Caliper and place the sphere or cylinder between the two jaws and adjust the movable jaw, such that it gently grips the body without any undue pressure on it. That done, tighten the screw attached to the Vernier scale.
Note the position of the zero mark of the Vernier scale on the main scale. Record the main scale reading just before the zero mark of the Vernier scale. This reading (N) is called main scale reading (MSR).
Note the number (n) of the Vernier scale division which coincides with the division of the main scale.
You'll have to repeat steps 5 and 6 after rotating the body by 90o for measuring the diameter in a perpendicular direction.
Repeat steps 4 to 7 for three different positions and record the observations.
Now find total reading using the equation, TR = MSR+VSR = N+(n x L.C) and apply the zero correction.
Take the mean of the different values of the diameter and show that in the result with the proper unit.

For Screw Gauge:
Determine the pitch and least count of the screw gauge using the equations (1) and (2) respectively.
Bring the anvil and screw in contact with each other and find the zero error. Do it three times and record them. If there is no zero error, then record ‘zero error nil’.
Move the screw away from the anvil and place the lead shot and move the screw towards the anvil using the ratchet head. Stop when the ratchet slips without moving the screw.
Note the number of divisions on the pitch scale that is visible and uncovered by the edge of the cap. The reading N is called the pitch scale reading(PSR)
Note the number (n) of the division of the circular scale lying over the reference line.
Repeat steps 4 and 5 after rotating the lead shot by 900 for measuring the diameter in a perpendicular direction. Record the observations in the tabular column.
Find total reading using the equation 3 and apply zero correction in each case.
Take the mean of different values.
Calculation:
Vernier Calipers:
Zero Error Calculation:
Zero error, C= 0 cm
Volume of the sample (Iron Block): V=l×b×h=〖cm〗^3

Screw Gauge:
Zero Error Calculation:
Zero error, C= -2 × 0.001= -0.002 cm
Volume of the sample (Lead shot): V=4/3 π〖(D/2)〗^3=〖 cm〗^3

Results and Discussions:

Volume of the sample (Iron Block) using Vernier Calipers:〖 cm〗^3

Volume of the sample (Lead shot) using Screw Gauge:〖cm〗^3