• # question_answer In an experiment the angles are required to be measured using an instrument 29 deviation of the main scale exactly coincide with the 30 deviation of the vernier scale. If the smallest division of the main scale is half - a - degree $(={{0.5}^{o}})$, then the least count of the instrument is: A)  one minute                    B)  half minute C)  one degree                    D)  half degree

The least count $=\frac{value\,of\,main\,scale\,division}{number\,of\,divisions\,on\,verinier\,scale}$$=\frac{1}{30}\,MSD\,=\frac{1}{30}\,\times \frac{{{1}^{0}}}{2}=\frac{{{1}^{0}}}{60}=1\,\min$