Question

Aman measured the length of a book with a broken scale and recorded his reading to be 15 cm .His scale was broken and was not showing the initial readings till 2 cm .He started to measure from 3 cm onwards . What would be exact reading of the table

Answer 1

Answer:

The measured distance by the student is 3.50 cm which means the least count of the measurement done is 0.01 cm.  

A  screw gauge having 100 divisions on a circular scale with a pitch of 1 mm will have a least count of (1 mm)/(100) i.e. 0.01 mm

similarly screw gauge having 50 divisions on a circular scale with a pitch of 1 mm will have a least count of (1 mm)/(50) i.e. 0.5 mm

A meter scale has a least count of 1 mm.

And the least count of a  vernier caliper which has 10 divisions  in 1 cm on main scale and 10 divisions in vernier scale match with 9 division in main scale can be given as  

1 cm/(10*10) = 0.01 cm

Thus the student must have used  the vernier caliper for the measurement.