The pitch of a screw gauge is 0.5 mm and the number of division on the circular scale is 100. When a glass plate is held between the studs of the screw gauge , the main scale reads 1.5 mm and the 69th division of the circular scale coincides with the index line of the main scale . What is the thickness of the glass plate ?

Explanation

(i) The mass of the empty specific gravity bottle `=m_(1)`
(ii) The mass of empty specific gravity (SG) bottle + oil `m_(2)`
(iii) The mass of empty specific gravity bottle + water =`m_(3)`
(iv) The mass of of oil `=m_(2) -m_(1)`
(v) The mass of water =`m_(3) -m_(1)`
(vii) the relative density of oil
`((m_(2) -m_(1))//v)/((m_(3)-m_(1))//v)= (m_(2)-m_(1))/(m_(3)-m_(1))`
(viii) Relative density of the oil =0.9