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Question
What do you understand by the term least count of screw?
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Solution
Least distance of the screw is defined as the smallest distance moved by its tip when the screw turns through one division marked on it.
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RELATED QUESTIONS
Fig., below shows the reading obtained while measuring the diameter of a wire with a screw gauge. The screw advances by 1 division on the main scale when circular head is rotated once.
Find:
(i) Pitch of the screw gauge,
(ii) Least count of the screw gauge and
(iii) The diameter of the wire.
Figure shows the position of vernier scale while measuring the external length of a wooden cylinder.
- What is the length recorded by the main scale?
- Which reading of vernier scale coincides with the main scale?
- Calculate the length.
(a) A vernier scale has 20 divisions. It slides over the main scale, whose pitch is 0.5 mm. If the number of divisions on the left hand of the zero of vernier on the main scale is 38 and the 18th vernier scale division coincides with the main scale, calculate the diameter of the sphere, held in the jaws of vernier callipers.
(b) If the vernier has a negative error of 0.04 cm, calculate the corrected radius of the sphere.
The thimble of a screw gauge has 50 divisions for one rotation. The spindle advances 1 mm when the screw is turned through two rotations.
- What is the pitch of the screw?
- What is the least count of screw gauge?
- When the screw gauge is used to measure the diameter of wire the reading on the sleeve is found to be 0.5 mm and reading on thimble is found, 27 divisions. What is the diameter of the wire in centimetres?
What do you understand by the following term as applied to screw gauge?
Positive zero error
State whether the following statement is true or false by writing T/F against it.
The least count of a screw gauge can be lowered by increasing the number of divisions on its thimble.
The following diagrams (Fig. 5) show the use of a vernier caliper under three different situations. Study the diagrams carefully and note down the vernier readings in each case.
(a) Measuring the diameter of the rod
(b) Measuring Internal diameter of a cavity
(c) Measuring depth of a cavity
