Question
Question: Pitch of screw gauge is 1 mm. There are 100 divisions on circular scale. While measuring diameter of...
Pitch of screw gauge is 1 mm. There are 100 divisions on circular scale. While measuring diameter of wire the linear scale reads 1 mm and 45th division of circular scale coincides with reference line of main scale. Length of wire is
5.0 cm measured by metre scale. The surface area of wire to correct significant figure is –
A
2.32 cm2
B
23.2 cm2
C
2.30 cm2
D
23 cm2
Answer
2.30 cm2
Explanation
Solution
2r = 1+ 0.45 = 1.45 mm = 0.145 cm
CSA = 2prl = 0.145 × 3.14 × 5 = 2.27
CA = 2prl2 = 2 × 3.14 × (0.0725)2 = 0.030
SA = CSA + CA = 2.27 + 0.030 = 2.30 cm2