Question

A torsion balance has a sensitivity requirement (SR) of 4.5 mg. What is the MWQ of this balance if the maximum error permitted in using it is 3.6%?

Answer 1

Explanation:

MWQ means the minimum weighable quantity.

Mathematically,         MWQ = $\frac{Sensitivity}{1 - \text{fraction of accuracy}}$

or,        MWQ = $\frac{sensitivity}{\text{fractional error}}$

It is given that sensitivity is 4.5 mg and maximum permitted error is 3.6%.

Therefore, fraction error = $\frac{3.6}{100}$ = 0.036

Hence, we will calculate MWQ as follows.

                  MWQ = $\frac{sensitivity}{\text{fractional error}}$

                            = $\frac{4.5 mg}{0.036}$

                            = 125 mg

Thus, we can conclude that the MWQ of the given balance is 125 mg.