1
JEE Main 2025 (Online) 23rd January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language
The energy of a system is given as $\mathrm{E}(\mathrm{t})=\alpha^3 \mathrm{e}^{-\beta t}$, where t is the time and $\beta=0.3 \mathrm{~s}^{-1}$. The errors in the measurement of $\alpha$ and $t$ are $1.2 \%$ and $1.6 \%$, respectively. At $t=5 \mathrm{~s}$, maximum percentage error in the energy is :
A
$6 \%$
B
$11.6 \%$
C
$4 \%$
D
$8.4 \%$
2
JEE Main 2025 (Online) 23rd January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

Match List - I with List - II

List - I List - II
(A) Permeability of free space (I) $\left[\mathrm{M} \mathrm{L}^2 \mathrm{~T}^{-2}\right]$
(B) Magnetic field (II) $\left[\mathrm{M} \mathrm{T}^{-2} \mathrm{~A}^{-1}\right]$
(C) Magnetic moment (III) $\left[\mathrm{M} \mathrm{L} \mathrm{T}^{-2} \mathrm{~A}^{-2}\right]$
(D) Torsional constant (IV) $\left[\mathrm{L}^2 \mathrm{~A}\right]$

Choose the correct answer from the options given below :

A
(A)-(III), (B)-(II), (C)-(IV), (D)-(I)
B
$(\mathrm{A})-(\mathrm{I}),(\mathrm{B})-(\mathrm{IV}),(\mathrm{C})-(\mathrm{II}),(\mathrm{D})-(\mathrm{III})$
C
$(\mathrm{A})-(\mathrm{II}),(\mathrm{B})-(\mathrm{I}),(\mathrm{C})-(\mathrm{III}),(\mathrm{D})-(\mathrm{IV})$
D
(A)-(IV), (B)-(III), (C)-(I), (D)-(II)
3
JEE Main 2025 (Online) 23rd January Morning Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The position of a particle moving on $x$-axis is given by $x(t)=A \sin t+B \cos ^2 t+C t^2+D$, where $t$ is time. The dimension of $\frac{A B C}{D}$ is

A
$\mathrm{L}$
B
$\mathrm{L}^3 \mathrm{~T}^{-2}$
C
$\mathrm{L}^2 \mathrm{~T}^{-2}$
D
$\mathrm{L}^2$
4
JEE Main 2025 (Online) 22nd January Evening Shift
MCQ (Single Correct Answer)
+4
-1
Change Language

The maximum percentage error in the measurment of density of a wire is

[Given, mass of wire $=(0.60 \pm 0.003) \mathrm{g}$

radius of wire $=(0.50 \pm 0.01) \mathrm{cm}$

length of wire $=(10.00 \pm 0.05) \mathrm{cm}]$

A
7
B
8
C
5
D
4
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