NTA Abhyas JEE Main2020PhysicsUnits and DimensionsPractice
Two full turns of the circular scale of a screw gauge cover a distance of 1 mm on its main scale. The total number of divisions on the circular scale is 50 . Further, it is found that the screw gauge has a zero error of - 0.03 mm . While measuring the diameter of a thin wire, a student notes the main scale reading of 3 mm and the number of circular scale divisions, in line with the main scale, as 35 . The diameter of
Options
- A3.38 mm
- B3.32   mm
- C3.73   mm
- D3.67   mm
Correct answer
A. 3.38 mm
Step-by-step solution
Least count of the screw gauge, = 0.5 mm 50 = 0.01 mm Main scale reading = 3 mm Vernier scale reading = 35 ∴ Observed reading = 3 + 0.35 = 3.35 mm Zero error = -0.03 mm ∴ Actual diameter of the wire = 3.35 - - 0.03 = 3.38 mm