The main scale of a vernier callipers reads 10 mm in 10 divisions. 10 divisions of Vernier scale coincide with 9 divisions of the main scale. When the two jaws of the callipers touch each other, the fifth division of the vernier coincides with 9 main scale divisions and the zero of the vernier is to the right of zero of main scale. When a cylinder is tightly placed between the two jaws, the zero of vernier scale lies slightly behind 3.2 cm and the fourth vernier division coincides with a main scale division. The diameter of the cylinder is.

(A)  3.10 cm

(B)  3.8 cm

(C)  3.09 cm

(D)  -3.09 cm

Concept Videos :-

#7 | Vernier Caliper
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#11 | Screw Gauge: Solved Examples

Concept Questions :-

Measuring devices

(C)

L.C. = 0.1 mm

 Zero error = 0.1 mm X 5 = 0.5 mm or 0.05 cm

Observed reading = 3.1 cm + 0.01 cm X 4 = 3.14 cm

Correct reading = 3.14 cm - 0.05 cm

                         = 3.09 cm

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