127. The cross-section of straight edges upto 180 mm length is
A.Rectangular
B.Circular
C.I-section
D.Elliptical

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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

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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

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130. The maximum munber of faces in precision polygons can be
A.6
B.72
C.12
D.20

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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

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132. Precision polygons are calibrated from first principles using
A.One autocollimator
B.Two autocollimators
C.Three autocollimators
D.Two precision spirit levels

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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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