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JEE Main 2022 (29 Jul, Shift 1) · Least Count, Vernier Callipers & Screw Gauge

Least Count, Vernier Callipers & Screw Gauge question from JEE Main 2022 (29 Jul, Shift 1)

Q30JEE Main 2022 · 29 JUL · SHIFT 1Easy

Least Count, Vernier Callipers & Screw Gauge

In an experiment to find out the diameter of wire using screw gauge, the following observations were noted:

Figure

(A) Screw moves 0.5 mm0.5\text{ mm} on main scale in one complete rotation

(B) Total divisions on circular scale =50= 50

(C) Main scale reading is 2.5 mm2.5\text{ mm}

(D) 4545th division of circular scale is in the pitch line

(E) Instrument has 0.03 mm negative error

Then the diameter of wire is:

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Answer: (c)

  1. LC =0.5 mm50=0.01= \dfrac{0.5\text{ mm}}{50} = 0.01 mm
  2. Observed reading =2.5+45×0.01=2.95= 2.5 + 45\times 0.01 = 2.95 mm
  3. Negative zero error −0.03-0.03 mm, so correct reading =2.95−(−0.03)=2.98= 2.95 - (-0.03) = 2.98 mm
  4. So the answer is (c) 2.982.98 mm.
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