Question

What is meant by least count ? In an ammeter there are 20 divisions between the 0 mark and 0.5 mark.

Find least count of ammeter ​

Answer 1

Answer:

(a) The minimum potential difference measured by a voltmeter between the two given terminals is called the least count of that voltmeter.

(b) Two given marks of the voltmeters= 0 and 0.5 V

Potential difference = 0.5 - 0 = 0.5 V

No. of divisions between these two marks = 20

Least count =0.520=520×10=140=0.025

volts

Explanation:

Answer 2

Least Count:

• Least count of any graduated instrument refers to the smallest difference between any consecutive markings.

• It can be calculated by dividing the total range of markings in that instrument with the total number of markings.

• Lesser the Least Count of any instrument , more accurate is that instrument.

In the ammeter , there are 20 markings between 0 mark and 0.5 mark.

$\rm \therefore \: least \: count = \dfrac{range}{total \: divisions}$

$\rm \implies \: least \: count = \dfrac{0.5 - 0}{20}$

$\rm \implies \: least \: count = \dfrac{0.5 }{20}$

$\rm \implies \: least \: count = 0.025 \: ampere$

So, least count (LC) of the ammeter is 0.025 A.