Question

A micrometer screw gauge is used to measure the diameter of a piece of wire. The following readings were obtained:
mean zero reading : $0.05\pm 0.02mm$, and

mean apparent diameter : $+1.05\pm 0.02mm$.
The diameter of the wire should be written as ?

• A. $1.00\pm 0.02mm$.
• B. $1.00\pm 0.04mm$.
• C. $1.10\pm 0.00mm$.
• D. $1.10\pm 0.04mm$.

Answer 1

The correct option is B $1.00\pm 0.04mm$.

$\begin{array}{cc}\text{Given -}& \text{Mean zero reading}=0.05\pm 0.02mm\\ & \text{Mean apparent diameter}=1.05\pm 0.02mm\end{array}$

$\begin{array}{c}\text{Reading}=1.05-0.05=1.00mm\\ \text{As Real reading = Reading - zero Error.}\end{array}$

$\begin{array}{c}\text{Now error in the Reading}\\ \text{error =}\begin{array}{c}\text{|Max error in measured reading |}\\ +\text{|Max error in measuring zero error|}\end{array}\end{array}$

$\begin{array}{c}=0.02mm+0.02mm\\ =0.04mm\end{array}$

$\text{Reading}=1mm\pm 0.04mm$