Question

A micrometer has 150 equal divisions on the

circular scale, and on one full rotation of circular

scale main scale advances by 0.02 cm on the main

scale. The least count of the micrometer (in cm) is​

Answer 1

Given:

A micrometer has 150 equal divisions on the circular scale, and on one full rotation of circular scale main scale advances by 0.02 cm on the main scale.

To find:

Least Count of micrometre in cm unit.

Calculation:

Kindly remember this method as it helps during practicals too when you need to calculate the LC of the micrometre in front of the teacher.

Least Count of a micrometre is defined as the pitch (distance moved by 1 full rotation) divided by the total number of divisions on the circular scale.

$\rm \therefore \: LC = \dfrac{pitch}{total \: divisions \: on \: circular \: scale}$

$\rm = > \: LC = \dfrac{distance \: moved \: upon \: 1 \: full \: rotation}{total \: divisions \: on \: circular \: scale}$

$\rm = > \: LC = \dfrac{0.02}{150}$

$\boxed{\rm = > \: LC = 0.00013 \: cm}$

Usually , it is asked to state the LC in "mm" unit, because all the small dimensions can be better expressed in "mm" unit.

$\boxed{ \rm = > \: LC = 0.13 \: mm}$

So, least count is 0.00013 cm.