Question

A student measures the thickness of a copper wire using standard instruments and reports it as $0.1{\text{ }}cm,{\text{ }}0.15{\text{ }}cm$ and $0.157{\text{ }}cm$. The instruments used to find these measurements are _____, ______ and _____ respectively.
(a)vernier calipers, ordinary scale, screw gauge
(b) ordinary scale, vernier calipers, screw gauge
(c) screw gauge, vernier calipers, ordinary scale,
(d)ordinary scale, screw gauge, vernier calipers

Answer 1

In order to find the instruments used in the three cases, firstly we need to observe the least count of the instruments in the options.

Complete Solution
Least count of the ordinary scale is that of the vernier scale is and that of screw gauge is. This means ordinary scale, vernier callipers and screw gauge can give measurements up to respectively. Thus is taken with the help of ordinary scale, is taken with the help of vernier callipers and is taken using screw gauge.

Thus, the correct option to this question is option (b).

Additional Information: It utilizes two graduated scales: a main scale similar to that on a ruler and an especially graduated auxiliary scale, the vernier, that slides parallel to the main scale and enables readings to be made to a fraction of a division on the main scale. Vernier calipers are widely used in scientific laboratories and in manufacturing for quality control measurements.The screw gauge is an instrument used for measuring exactly the diameter of a thin wire or the width of a sheet of metal. It comprises a U-shaped mount which is fixed with a screwed pin which is fixed to a thimble. Side by side to the axis of the thimble, a scale passed in mm is inscribed.

Note: While solving this question, we should know about different measuring instruments like vernier calipers, ordinary scale, screw gauge. Also, about their least count.