127. The cross-section of straight edges upto 180 mm length is
A.Rectangular
B.Circular
C.I-section
D.Elliptical
128. 'Optical micrometer is used to
A.Measure small linear displacements
B.Measure surface profiles
C.Measure surface roughness
D.Set very small displacement by rotating the glass block through relatively large angles
129. Airy points of support are
A.0.577 L apart
B.0.554 L apart
C.0.5 L apart
D.0.58 L apart
130. The maximum munber of faces in precision polygons can be
A.6
B.72
C.12
D.20
131. In precision polygon, a central hole and small holes are drilled through the thickness
A.For mounting purposes
B.To achieve high accuracy
C.For ease of manufacture
D.To make them light
132. Precision polygons are calibrated from first principles using
A.One autocollimator
B.Two autocollimators
C.Three autocollimators
D.Two precision spirit levels
133. The fact that how closely the instrument reading folloVis the measured variables is termed as
A.Fidelity
B.Accuracy
C.Threshold sensitivity
D.Precision
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