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Least count of spring balance, if spring balance has a range of 0-25 kg and consists of every kg increment in weight the needle moves by 10 divisions.
A. 100 g/mm
B. 0.0001 g/mm
C. 0.01 g/cm
D. 1 g/m

Answer Verified Verified
Hint: In this question, we first assume a spring balance whose range lies from 0-25kg. Then we know that in this scale the 1kg range is divided into a further 10 equivalent parts so that the least count can be determined by measuring a 1kg object and by counting the number of divisions that the needle is pointing upon when the weight is applied, which will be equal to 10 divisions. Hence the least count we get is 100 g/mm.

Complete Step-by-Step solution:
A spring balance is a measuring device used to measure the weight of objects accurately. A spring balance is a measuring device used to measure the weight of objects accurately. A spring balance consists of a spring which is fixed at one end and is connected with a hook to attach an object at the other. It works on Hooke's Law, which states, that when a force is applied to stretch a spring, it is proportional to the distance that spring is stretched from its rest state. Because of these the scale markings on the spring balance are always equally spaced.
Now we know that the least count of a measuring instrument is the least value of a physical quantity that can be measured accurately using the instrument. The least count of any measuring scale depends on the number of divisions that when the number of divisions is increasing the least count decreases in a similar fashion.
Let us assume a spring balance whose range lies from 0-25kg.
Here, we know that in this scale the 1kg range is divided into a further 10 equivalent parts.
$ \Rightarrow 1Kg = 1000g$
$ \Rightarrow \dfrac{{1000g}}{{10}} = 100g$
The least count can be determined by measuring a 1kg object and by counting the number of divisions that the needle is pointing upon when the weight is applied, which will be equal to 10 divisions.
So we get the least count as 0.1kg per division or 100g per division. Hence option A is correct.

Note: For these types of questions we need to know about some important measuring instruments that are Vernier caliper, spring balance, and screw gauge. Then we need to know how to use them for measuring and how to calculate the least count for them.