Screw Gauge Viva Questions and Answers

Screw Gauge Viva Questions and Answers
(i) Name the instrument used for measuring the thickness of a piece of paper

Ans: Screw gauge.

(ii) What is meant by pitch of a screw gauge?

Ans: It is the distance advanced by the screw for one complete rotation of the head.

(iii) The pitch of a screw is 1 mm and the number of divisions on the head scale is 100. What is the least count?

Ans: Least count =  pitch/ No: of divisions on the head scale = 1/100 = 0.01 mm

(iv) What is zero error of a screw gauge?

Ans: If the zero of the head scale does not coincide with the zero of the pitch scale when the end of the movable screw is in contact with the stud, the screw gauge is said to have zero error.

(v) If the zero of the head scale is 5 divisions above the line of graduation of the pitch scale when the gap is closed, what is the zero error? What is the zero correction? Least count of the vernier = 0.01 mm

Ans: zero error = -5 x 0.01 = -0.05 mm and zero correction = +0.05 mm

(vi) If the zero of the head scale is 5 divisions below the line of graduation of the pitch scale when the gap is closed, what is the zero error and correction? Least count = 0.01 mm

Ans: zero error = +5 x 0.01 = +0.05 mm and zero correction = -0.05 mm

(vii) Why do we take a number of observations for the diameter of a wire?

Ans: Even if the wire appears uniform it may not be true. So to take the average value we take a set of readings

(viii) Why do you stop rotating the screw as soon as the ratchet begins to turn between the fingers?

Ans: When the ratchet begins to turn, the two faces are in contact or in contact with the body held between them. The device avoids undue pressure on the screw.

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