JEE Main 2026 (Online) 23rd January Morning Shift | Units & Measurements Question 24 | Physics

Four persons measure the length of a rod as $20.00 \mathrm{~cm}, 19.75 \mathrm{~cm}, 17.01 \mathrm{~cm}$ and 18.25 cm . The relative error in the measurement of average length of the rod is :

0.18

0.24

0.06

0.08

JEE Main 2026 (Online) 22nd January Evening Shift

MCQ (Single Correct Answer)

-1

If $\epsilon, E$ and $t$ represent the free space permittivity, electric field and time respectively, then the unit of $\frac{\epsilon E}{t}$ will be :

$\mathrm{A} / \mathrm{m}$

$\mathrm{A} / \mathrm{m}^2$

$\mathrm{Am}^2$

JEE Main 2026 (Online) 22nd January Morning Shift

MCQ (Single Correct Answer)

-1

$$ \text { Match the LIST-I with LIST-II } $$

List-I		List-II
A.	Spring constant	I.	$M L^{2} T^{- 2} K^{- 1}$
B.	Thermal conductivity	II.	${ML}^{0} T^{- 2}$
C.	Boltzmann constant	III.	$M L^{2} T^{- 3} A^{- 2}$
D.	Inductive reactance	IV.	$M L T^{- 3} K^{- 1}$

Choose the correct answer from the options given below:

A-III, B-II, C-IV, D-I

A-I, B-IV, C-II, D-III

A-II, B-I, C-IV, D-III

A-II, B-IV, C-I, D-III

JEE Main 2026 (Online) 21st January Evening Shift

MCQ (Single Correct Answer)

-1

A spherical body of radius $r$ and density $\sigma$ falls freely through a viscous liquid having density $\rho$ and viscosity $\eta$ and attains a terminal velocity $v_0$. Estimated maximum error in the quantity $\eta$ is : (Ignore errors associated with $\sigma$, $\rho$ and $g$, gravitational acceleration)

$2 \left[ \frac{\Delta r}{r} - \frac{\Delta v_0}{v_0} \right]$

$2 \left[ \frac{\Delta r}{r} + \frac{\Delta v_0}{v_0} \right]$

$\frac{2 \Delta r}{r} + \frac{\Delta v_0}{v_0}$

$2 \frac{\Delta r}{r} - \frac{\Delta v_0}{v_0}$

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