Question

Least count of ammeter and voltmeter are ?

Answer 1

Least count is the smallest measurement that can be taken by a measuring instrument. In metrology, the least count of a measuring instrument is the smallest change in the measured quantity that can be resolved on the instruments scale.

Complete step by step answer:
The least count of a measuring instrument is the smallest and accurate value in the measured quantity that can be resolved on the instrument’s scale.
The least count is related to the precision of an instrument.
Basically, An Ammeter has a range of $0-3A$ and there 30 divisions on the ammeter
Range is basically the difference between maximum value to the minimum value.
So the range of ammeter =3-0= 3 A

Hence, $Least\,count\,of\,ammeter\,=\,\dfrac{Range\,of\,ammeter}{Total\,number\,of\,division\,on\,the\,ammeter\,scale}$
$=\dfrac{3}{30}=0.1A$
For voltmeter, there are 20 divisions for a voltmeter between $0-0.5V$ marks. Means $0.5$ volt is equal to 20 divisions.
So, the range of voltmeter=0.5-0=0.5V
Hence, $Least\,count\,of\,voltmeter\,=\,\dfrac{Range\,of\,voltmeter}{Total\,number\,of\,division\,on\,the\,voltmeter\,scale}$
$=\dfrac{0.5}{20}=0.025V$
Therefore the least count of ammeter is 0.1A and least count of voltmeter is 0.02A

Note:
There are different types of ammeter and voltmeter is used having different least count. But Least count is directly connected with precision means lesser the least count the instrument will be accurate or precise more.
$\text{Least Count}=\dfrac{\text{Value of one main scale division}}{\text{Total number of scale division}}$
Basically, an ammeter is always connected in series with the circuit to be measured, whereas a voltmeter is always in parallel in a circuit. Ammeter is device which is used to measure the