Question

What is the least count of steel rules ?

Answer 1

All of us had used scale in our student life. We know how to use it but there are some details and rules of scale. Industrial name is Steel rule. We take measurements of length using this scale. It is mainly for the linear measurement with steel rule or steel tape. Least count is defined as the minimum measurement that can be made using the particular instrument.

Complete answer:
Least count of an instrument is defined as the least measurement that can be done using that particular instrument. Let us now understand the Steel Rule and its least count-
(i) It is straightedge with equal spaced markings with line.
(ii) Its sides are right angled and parallel to each other.
(iii) It is used to measure distances or to rule straight lines.
(iv) It is available in different lengths, the common sizes being 150 mm, 300 mm, and 600 mm.
(v) Its least count or reading accuracy is $0.5{\text{ }}mm$.
(vi) In English system of Linear units the least count is $\dfrac{1}{{64}}$ inch.

The available sizes of steel rule used in daily life or in daily work is $6^{‘’},12^{‘’},24^{‘’}$ and equivalent to the metric size that is in cm. Steel tapes are available in $6{\text{ }}ft$, ${\text{15 }}ft$, ${\text{25 }}ft$ and ${\text{50 }}ft$ and also available in Indian system.

Note: If we use a metre scale for measurement of length, it may have graduations at $1{\text{ }}mm$ division scale spacing or interval. A Vernier scale on a caliper has a least count of $0.01{\text{ }}mm$ while a micrometer may have a least count of $0.001{\text{ }}mm$. The least count error occurs with both systematic and random errors.