Question

An ammeter has a range of $0 - 3$ ampere and there are $30$divisions in its scale. Calculate the least count of the ammeter.

Answer 1

In order to solve this question, we are first going to define what the least count of an instrument is and how it is expressed mathematically. Then, after writing the formula for the least count of the ammeter and assessing the information given in the question, the least count of ammeter is found.

Formula used:
The formula for the least count of any instrument is the ratio of the range of the instrument to the total number of the divisions. It is given by the equation:
$L.C. = \dfrac{{Range}}{{total\,number\,of\,divisions}}$

Complete step-by-step solution:
The least count of an instrument is defined as the smallest and the accurate value in the measured quantity that can be resolved on the instrument’s scale.
Mathematically, it is given as the ratio of the range of the instrument to the total number of the divisions. It is given by the equation:
$L.C. = \dfrac{{Range}}{{total\,number\,of\,divisions}}$
Now, in the question, it is given that
The range of the ammeter is equal to $0 - 3A$
The total number of the divisions are$30$
Thus, the least count is calculated as
$L.C. = \dfrac{3}{{30}} = 0.1$
Thus, the least count of the ammeter is$0.1A$.

Note: It is important to note that the range of the ammeter is calculated by subtracting the lower limit of the range from the upper limit value of the range. That is in this case, we can see that the range is $0 - 3A$
Hence, value of range is equal to : ${A_R} = 3A$