Question

The length of two rods measured by a meter scale are 60.0 cm and 20.0 cm respectively. The least count of meter scale is 1 mm. Then

• A. First measurement is more accurate
• B. Second measurement is more accurate
• C. Both measurement are equally accurate
• D. First measurement is more is more precise

Answer 1

Answer: (C), (D)

Both measurement are equally accurate
First measurement is more is more precise

$\begin{array}{cc}\text{Given -}& \text{Length of Rod}1\text{measured}=60.0cm\\ & \text{Length of Rod}2\text{measured}=20.0cm\\ & \text{Least count of Scale}=1mm=0.1cm\end{array}$

$\begin{array}{c}\text{Both the Readings are equally accurate because}\\ \text{the meauswred units are accurate upto the least}\\ \text{count}=0.1cm\\ \text{and hence both are equaly accurate.}\end{array}$

$\begin{array}{c}\text{Percentage error in Rod}1=\frac{0.1}{60}=0.16\%\\ \text{Percentage error in Rod}2=\frac{0.1}{20}=0.5\%\\ \text{since}\%\text{eeror in Rod}1<\%\text{error in Rod}2\\ \text{Hence Reading of Rod}1\text{is more precise.}\end{array}$