JEE Main 2021PhysicsExperimental PhysicsHardNumerical

JEE Main 2021 — Experimental Physics Question with Solution

JEE Main 2021 (31 Aug Shift 2)

Question

The diameter of a spherical bob is measured using a vernier callipers. 9 divisions of the main scale, in the vernier callipers, are equal to 10 divisions of vernier scale. One main scale division is 1 mm. The main scale reading is 10 mm and 8th division of vernier scale was found to coincide exactly with one of the main scale division. If the given vernier callipers has positive zero error of 0.04 cm, then the radius of the bob is _____________ ×10-2 cm.

Enter your answer

Show full solutionCorrect answer: 52
Correct answer
52

Step-by-step explanation

9 MSD=10 VSD
1 VSD=0.9 mm
1 MSD=1 mm
∴ L.C.=MSD-VSDMSD=1-0.91=0.1
Reading = Main scale reading + L.C. × vernier scale reading
=10+0.1×8
=10.8 mm

Reading of diameter=10.8 mm-0.4 mm=10.4 mm
radius of the bob=5.2 mm
=0.52 cm=52×10-2 cm

Practice this on the real CBT interface

Solve this JEE Main question (and the rest of the Experimental Physics chapter) on PrepSharp's TCS iON-style CBT player — with timer, bookmarks and session analytics.

Solve interactively →

About this question

This is a previous-year question from JEE Main 2021, covering the Experimental Physics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.