In a screw gauge, there are 100 divisions on the circular scale and the main scale moves by 0 . 5 mm on a complete rotation of the circular scale. The zero of circular scale lies 6 divisions below the

Question

In a screw gauge, there are 100 divisions on the circular scale and the main scale moves by 0 . 5 mm on a complete rotation of the circular scale. The zero of circular scale lies 6 divisions below the line of graduation when two studs are brought in contact with each other. When a wire is placed between the studs, 4 linear scale divisions are clearly visible while 46 th division the circular scale coincide with the reference line. The diameter of the wire is ______ × 10 - 2 mm .

TestHub · Accepted Answer

Least count of screw gauge is = Pitch No . of circular divisions = 0 . 5 mm 100 Least count, L C = 5 × 10 - 3 mm The zero of circular scale lies 6 divisions below the line of graduation. So, zero error is positive. Positive zero error = M S R + C S R ( L C ) = 0 mm + 6 5 × 10 - 3 mm Diameter of wire, d = M S R + C S R ( L C ) – Positive zero error = 4 × 0 . 5 mm + 46 5 × 10 - 3 - 6 5 × 10 - 3 mm = 2 mm + 40 × 5 × 10 - 3 mm = 2 . 2 mm Hence, diameter of wire is 220 × 10 - 2 mm .

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