Exams › JEE Main › Physics
A rod was found to have a measured length of 3.50 cm. Which measuring device was used for this reading?
- A metre rule
- A vernier caliper in which 10 vernier divisions coincide with 9 main-scale divisions, and the main scale has 10 divisions in 1 cm
- A screw gauge with 100 circular-scale divisions and a pitch of 1 mm
- A screw gauge with 50 circular-scale divisions and a pitch of 1 mm
Correct answer: A vernier caliper in which 10 vernier divisions coincide with 9 main-scale divisions, and the main scale has 10 divisions in 1 cm
Solution
A reading of 3.50 cm is given to 0.01 cm (0.1 mm). For the vernier where 10 VSD = 9 MSD and 1 MSD = 1 mm, least count = 1 MSD/10 = 0.1 mm = 0.01 cm, matching the reading. The screw gauges give 0.001 cm or 0.002 cm (three decimals), and a metre rule only 0.1 cm.
Related JEE Main Physics questions
- A body has a measured mass of 5.00 ± 0.05 kg and a measured volume of 1.00 ± 0.05 m³. What is the maximum possible percentage error in its density?
- A substance has a density of 4 g/cm³ in the CGS system. If a new unit system is used where the unit of length is 10 cm and the unit of mass is 100 g, what is the numerical value of the density in that system?
- Which of the following physical quantities has dimensions that do not match the other three?
- If the percentage uncertainties in measuring mass M, length L, and time T are 1%, 1.5%, and 3% respectively, what is the percentage error in a quantity having dimensions M L⁻¹ T⁻¹?
- If E, m, J and G denote energy, mass, angular momentum and the gravitational constant, respectively, then the dimensional formula of EJ²/(m⁵G²) is identical to that of which quantity?
- In a screw gauge, two complete rotations of the circular scale advance the spindle by 1 mm on the main scale, and the circular scale has 50 equal divisions. The instrument is known to have a zero error of -0.03 mm. When the diameter of a fine wire is measured, the main scale reading is 3 mm and the circular scale division coinciding with the reference line is 35. What is the wire’s diameter?
⚔️ Practice JEE Main Physics free + battle 1v1 →