JEE Mains · Physics · STD 11 - Units,dimensions and measurement
- JEE Mains 2021
- Hard
- MCQ
In a Screw Gauge, fifth division of the circular scale coincides with the reference line when the ratchet is closed. There are \(50\) divisions on the circular scale, and the main scale moves by \(0.5 \,{mm}\) on a complete rotation. For a particular observation the reading on the main scale is \(5\, {mm}\) and the \(20^{\text {th }}\) division of the circular scale coincides with reference line. Calculate the true reading. (in \({mm}\))
Pick an option to check your answer.
Answer & Solution
Correct Answer
(C) \(5.15\)
Step-by-step Solution
Detailed explanation
Least count \(({L} \cdot {C})=\frac{0.5}{50}\)
True reading \(=5+\frac{0.5}{50} \times 20-\frac{0.5}{50} \times 5\)
\(=5+\frac{0.5}{50}(15)=5.15\, {mm}\)
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