JEE PYQ: Experimental Physics Question 6
Question 6 - 2020 (02 Sep 2020 Shift 1)
The least count of the main scale of a vernier callipers is 1 mm. Its vernier scale is divided into 10 divisions and coincide with 9 divisions of the main scale. When jaws are touching each other, the $7^{\text{th}}$ division of vernier scale coincides with a division of main scale and the zero of vernier scale is lying right side of the zero of main scale. When this vernier is used to measure length of a cylinder the zero of the vernier scale between 3.1 cm and 3.2 cm and $4^{\text{th}}$ VSD coincides with a main scale division. The length of the cylinder is: (VSD is vernier scale division)
(1) 3.2 cm
(2) 3.21 cm
(3) 3.07 cm
(4) 2.99 cm
Show Answer
Answer: (3)
Solution
L.C. of vernier callipers $= 1 \text{ MSD} - 1 \text{ VSD} = \left(1 - \frac{9}{10}\right) \times 1 = 0.1 \text{ mm} = 0.01$ cm. Zero error $= 7 \times 0.1 = 0.7 \text{ mm} = 0.07$ cm. Length of the cylinder $=$ measured value $-$ zero error $= (3.1 + 4 \times 0.01) - 0.07 = 3.07$ cm.
BETA
