Question

The vernier scale of a travelling microscope has $50$ divisions which coincide with $49$ main scale divisions. If each main scale division is $0.5\, mm$, then the least count of the microscope is

• A. $0.01\,cm$
• B. $0.5\,mm$
• C. $0.01\,mm$
• D. $0.5\,cm$

Answer 1

Answer: (C)

$0.01\,mm$

Answer 2

$1 \,MSD = 0.5 \,mm$ $50 \,VSD = 49 \,MSD$ $1\,VSD=\frac{49}{50}\,MSD$ Least count $= 1 \,MSD - 1 \,VSD$ $=1\,MSD-\frac{49}{50}\,MSD=\frac{1}{50}\,MSD$ $=\frac{1}{50}\times0.5\,mm=0.01\,mm$