CDF POINTS
1.Screw gauge works on the principle of screw in a nut.
2.Pitch of the screw, P = \(
\frac{{Dis\tan cetravelledbythescrew}}
{{No.ofcompleterotaionsmade}}
\) = \(
\frac{x}
{n}
\)
3.Least count (L.C) = \(
\frac{{pitchofthescrew}}
{{No.ofheadscaledivisions}}
\)
L.C = \(
\frac{P}
{N}
\)
4.The thickness of the wire can be measured by using the formula.
Thickness = P.S.R+(H.S.R. x L.C)
5.Positive error : When the zero of circular scale is left behind the reference line, then the instrument is said to have positive error and the correction is negative . Correction = - Coinciding division of C.S x L.C
Corrected diameter = Observed diameter +Correction.
6. Negative zero error : When the zero of circular scale advances beyond the reference line the instrument is said to have negative error and the correction is positive
Correction = +[n - coinciding division of C.S x L.C]