Question

The length of on rod $l_1=3.323cm$ and the other is $l_2=3.321cm$. Both rods were measured with one measuring instrument with least count 0.001 cm. Then $(l_1-l_2)$ is :

• A. $(0.002\pm 0.001)cm$
• B. $(0.002\pm 0.000)cm$
• C. $(0.002\pm 0.002)cm$
• D. none of these

Answer 1

The correct option is C $(0.002\pm 0.002)cm$

The error in two readings always adds up.
$l_1-l_2=(3.323\pm 0.001)-(3.321\pm 0.001)=(0.002\pm 0.002)cm$