A student uses a screw gauge to measure the thickness of a glass plate. The pitch of the screw gauge is 0.5 mm and it has 50 divisions on its circular scale. The main scale reading is 1.5 mm and the 24^ th division of the circular scale coincides with the reference line. What is the thickness of the glass plate?

Step-by-step solution

Least count of the screw gauge is given by the ratio of pitch to the number of divisions on the circular scale. Least count (LC) = 0.5 mm 50 = 0.01 mm The thickness of the glass plate is the sum of the main scale reading and the circular scale reading multiplied by the least count. Thickness = MSR + ( CSR LC ) Thickness = 1.5 mm + (24 0.01 mm ) Thickness = 1.5 mm + 0.24 mm = 1.74 mm Converting the thickness into centimeters: Thickness = 0.174 cm Answer: 0.174 cm