Question

The thin metallic strip of vernier callipers moves downward from top to bottom in such a way that it just touches the surface of beaker. Main scale reading of calliper is 6.4 cm whereas its vernier constant is 0.1 mm. The 4th of vernier scale division is coinciding with main scale division. The actual depth of beaker in mm is (when zero of vernier coincides with zero of main scale).A. 6.64 cm
B. 6.42 cmC. 6.44 cm
D. 6.13 cm

Answer 1

Final Answer : C : 6.44cm

Steps:
1) Since,Both scale zeroes are coinciding, so there is no zero error.

We have,
Least Count = 0.1mm = 0.01cm
Main Scale Reading (in cm ) = 6.4
Vernier Scale Reading, It's division which coincides with main scale = 4

2) So,We know
Depth of Beaker,
d = Main Scale Reading + Vernier Scale Reading * Least Count
d = 6.4cm + 4*0.01cm
= 6.4 + 0.04 = 6.44cm

Hence, Depth of Beaker = 6.44cm = 64.4mm.