Question

can anyone explain me the practical of screw gauge ...

plz :(
don't spam
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Answer 1

Explanation:

It's actually simple.

Only you have to how three thinks,they are

1)Positive error (above 0)

2)zero error(at zero)

3)Negative error(below zero that's means 100,90,80).

HOPE THIS WILL USEFUL.

Answer 2

$\sf \Large Answer!!$

Let's know the principle on which the screw gauge works.

It is used to measure the diameter of wire or thickness of paper, etc., usually correct up to 0.001 cm. However, the least count of a micrometre screw gauge is 1 μ (or 0.0001 cm).

The main parts of the screw gauge are:-

=> Ratchet

Function → To advance the screw by turning it till the object is gently held between the stud and the spindle of the screw.

=> Sleeve

Function → To mark main scale and base line.

=> Thimble

Function → To mark the circular scale

=> Main scale

Function → To read length correct up to 1 mm.

=> Circular scale

Function → Helps to read length correct up to 0.01 mm.

Pitch and least count of a screw gauge

The pitch of a screw gauge is the linear distance moved by its screw along the main scale when the circular scale is rotated by one division on it.

Least count = (Pitch of the screw gauge) ÷ (Total number of divisions on its circular scale)

Ways to decrease the least count:-

(a) Decrease the pitch

(b) Increase the total number of divisions on the circular scale

Zero error in a screw gauge → Due to mechanical error, on bringing the stud A on contact with the stud B, the zero mark of the circular scale is either below or above the base line of the main scale. If the zero mark is below the base line of the main scale, it is said to be positive zero error. If the zero mark is above the base line of the main scale, it is said to be negative zero error.

To find the correct reading, the zero error with its sign is subtracted from the observed reading.

The experiment is to measurement of diameter of a wire with a screw gauge.

Procedure:-

(a) Find the least count and the zero error (if any) of the screw gauge.

(b) Turn the ratchet anticlockwise to obtain a gap between the stud A and the flat end B. Place the wire in the gap. Turn the ratchet clockwise to hold the wire gently.

(c) Note the main scale reading.

(d) Note that division p of the circular scale which coincides with the base line of the main scale. Circular scale reading = p × Least count

(e) Add the circular scale reading to the main scale reading to obtain the observed diameter of the wire.

(f) Repeat it by keeping the wire in perpendicular direction. Take two more observations at different places of the wire and record them.

Observation:-

Pitch of the screw = ... cm

Total number of divisions on circular scale = ...

Least count = Pitch ÷ Number of divisions on circular scale

Least count = ... cm

Zero error = ...

Mean observed diameter = ... cm

Observed diameter = Main scale reading + (Circular scale division p coinciding the base line of the main scale × Least count)

True diameter = Observed diameter - zero error (with sign)