A micrometer is made using a bar having 20 threads per cm . On its circular scale it has 100 divisions. A student reads 5 divisions after 1 cm mark on linear scale and 37 division of circular scale, c

Question

A micrometer is made using a bar having 20 threads per cm . On its circular scale it has 100 divisions. A student reads 5 divisions after 1 cm mark on linear scale and 37 division of circular scale, coinciding with mainscale for the diameter of a cylinder. Write the diameter.

TestHub · Accepted Answer

The least count of the micrometer is 20 × 100 1 ​ = 0.0005 cm. The main scale reading is 1.25 cm (1 cm + 5 divisions, each division being 1/20 cm = 0.05 cm). The circular scale reading is 37 divisions, which is 37 × 0.0005 = 0.0185 cm. Therefore, the diameter is 1.25 + 0.0185 = 1.2685 cm. The correct answer with error is 1.2685 ± 0.0005 cm.

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