Question

a screw gauge has a screw having 2 threads in 1mm. the circular scale has 50 divisions . find the diameter of a wire,if the main scale shows 6th division and the circular reads 4.

Answer 1

Given,

i) Pitch of the screw gauge = 1 mm

ii) No. of circular scale division = 50

iii) error in the given instrument = 0

iv) main scale division (MSD) = 6

v) circular scale division (CSD) = 4

∴ Least Count (LC) = Pitch ÷ No. of circular scale division    ⇒ 1 ÷ 50

 ⇒ 0.02 mm

So,

Main scale reading(MSR) = MSD * pitch  ⇒ 6 * 1

⇒ 6 mm

Now,

length observed = MSR + (LC * CSD)    ⇒ 6 + (0.02 * 4)

⇒ 6.08 mm

So, the diameter of the wire,

actual length = length obseved - error    ⇒ 6.08 - 0

Ans. ⇒ 6.08 mm