1
In a screw gauge, the zero of the circular scale lies 3 divisions above the horizontal pitch line when their metallic studs are brought in contact. Using this instrument thickness of a sheet is measured. If pitch scale reading is 1 mm and the circular scale reading is 51 then the correct thickness of the sheet is mm. [Assume least count is 0.01 mm]
- 1.54
- 1.50
- 1.51
- 1.48
Answer
(1) 1.54
Solution
When the zero of the circular scale lies above the pitch (reference) line, the instrument reads less than the true value: the zero error is negative.
Zero error = -3 0.01 = -0.03 mm
Observed reading = 1 + 51 0.01 = 1.51 mm
Correct reading = observed reading − zero error
t = 1.51 - (-0.03) = 1.54 mm
Answer: (1)
JEE Main 2026 (Online) 23rd January Morning Shift