Question

How can the least count of a screw gauge be increased ?
A) Increasing number of divisions on circular scale
B) Increasing number of divisions of linear scale
C) Increasing pitch of screw gauge
D) All of the above

Answer 1

Hint:
We know that the least count of a screw gouge is the ratio of value of one main scale division to the total number of divisions on the Vernier scale. So in order to increase the least count of screw gauge just increase the value of one scale division by increasing the number of divisions on circular scale or linear scale.

Complete step-by-step answer:
In order to increase or decrease the least count of any instrument, first of all we need to understand the actual meaning of the least count.
When we measure anything, the smallest value that can be measured by the measuring instrument is called the least count of that measuring instrument.
The least count of screw gauge is defined as the ratio between the pitch of the screw and total number of divisions on circular scale on screw gouge.
\[L.C. = \dfrac{{Pitch}}{{C.S.D.}}\]
Hence on increasing the pitch of the screw gouge the least count of a screw gauge can be decreased.
 It is also defined as the ratio between the number of divisions on the linear scale (Main scale) and total number of divisions on circular scale (Vernier scale) of the screw gouge.
\[L.C. = \dfrac{{M.S.D.}}{{C.S.D.}}\]
Where
L.C. = Least count of screw gauge
M.S.D. = Main scale division of screw gauge
C.S.D. = Circular scale division of screw gauge
Hence on increasing the linear scale or decreasing the circular scale of screw gauge we can increase the least count of screw gauge.
By final conclusion we get that by increasing the number of divisions on the linear scale as well as by increasing the pitch of the screw gouge, we can increase the least count of screw gauge.
Hence the correct options are B and C.

Note:
One should take care of the least count error while measurement because the least count is the smallest and accurate value in the measured quantity that can be resolved on the instrumental scale. The least count occurs with both systematic and random errors. Instrument of higher precision can reduce the least count error.