Correct Answer - Option 3 : 113 mm
Concept:
In a tension test on a bar, gauge length means the length over which extension is measured.
\(GL = 5.65\;\sqrt {{A_o}}\)
Where Ao = Initial cross-sectional area before loading
Gauge length is independent of the length of a bar, material of bar, and shape of cross-section.
Calculation:
Given,
Ao = 50 × 8
\({\rm{Guage\;length}} = 5.65\;\sqrt {50 × 8} = 113\;{\rm{mm}}\)