Question

Which of the following is not a reading of meter scale?
A)2.5cm
B) 15cm
C) 1.5mm
D) 0.4m

Answer 1

HInt: A meter scale is used for measuring length of an object and as a marking length on paper for educational purposes. The meter scale or ruler is marked with centimeters on edges and the least count of a metre scale is 1mm or 0.1cm.

Complete step by step solution:
The meter scale is marked with centimetres on one edge and inches marked on another edge. Centimetres have decimal divisions while inches have fractional divisions.Meter scale may have bevelled edges to avoid errors due to parallax.
Least count is the smallest measurement that can be taken accurately with an instrument or device. The least count of a metre scale is 1mm or 0.1cm.
Now let's check the above possibility of each measurement.
2.5cm = 2.5$\times$10=25mm
15cm = 15$\times$10=150mm
0.4m = 0.4$\times$1000=400mm
1.5mm = 1.5 mm is not possible as it is not an integral multiple of 1mm.

Hence option (C) is not a reading of meter scale as 1.5mm is not an integral multiple of 1mm.

Note: The metric scale is the system of measurement used in the metric system. In the metric scale, 10 centimeters are equal to one decimeter, 10 decimeters are equal to one meter and 1,000 meters are equal to one kilometer.