Metre Rule

The metre rule can measure length up to a maximum of 1 metre and is usually made of wood
or metal. The smallest division is 1 mm or 0.1 cm and hence the accuracy of this instrument
is up to 0.5 mm.

In using the metre rule, you have to avoid parallax errors. Parallax errors occur due to the 

wrong positioning of the eye or the object is not at the same level as the markings of the 

scale. The eye position must be vertical or perpendicular to the mark to be read or else 

parallax error may occur. 

Important!!!!!!!!!!!!

Readings on the metre rule cannot be more than 1 decimal place measured in "cm" for Precision

   >Examples: 4.50 cm or 3.05 cm is correct but not 4.47 cm or 3.11 cm 

But still there are ways to avoid parallax errors:

>Use a thin ruler 

>Ensure that eye is placed vertically above the mark to be read 

>One way to improve accuracy of the experiment is take several (3 to 4) readings and 

find the average.