Which of the followig inctruemnts has minium least count?

1.	Which of the followig inctruemnts has minium least count?
Answer» A screw gauge of PITCH 1 mm and 100 divisions n the CIRCULAR scale. A spherrrometer of pitch 0.1 mm and 100 divisions on the circular scale. An optical intrument that can MEASURE length to within a wavelength of light. Solution :Least count of vernier callipers `=1MSD-1VSD=1MSD-(19)/(20)MSD` `=(1)/(20)MSD=(1)/(20)mm=(1)/(200)cm=0.005cm` (b) Least count of screw gauge `=("Pitch")/("No. of divisions ono circular scale")` `=(1)/(100)mm=(1)/(1000)cm=0.001m` (c) Least count of spherometer `=("Pitch")/("No. of divions on circular scale")` `=(0.1mm)/(100)=(1)/(1000)mm=0.0001cm` (d) Wavelength of light `lamda~~10^(-5)cm=0.00001cm` CLEARLY the optical instrument is the most precise.

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