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JEE Main 2025 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
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An electric dipole of mass $m$, charge $q$, and length $l$ is placed in a uniform electric field $\vec{E} = E_0\hat{i}$. When the dipole is rotated slightly from its equilibrium position and released, the time period of its oscillations will be :

A

$ \frac{1}{2\pi} \sqrt{\frac{ml}{2qE_0}} $

B

$ 2\pi \sqrt{\frac{ml}{2qE_0}} $

C

$ 2\pi \sqrt{\frac{ml}{qE_0}} $

D

$\frac{1}{2 \pi} \sqrt{\frac{2 \mathrm{~m} l}{\mathrm{q} \mathrm{E}_0}}$

2
JEE Main 2025 (Online) 29th January Morning Shift
MCQ (Single Correct Answer)
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Match List - I with List - II.

List - I List - II
(A) Electric field inside (distance r > 0 from center) of a uniformly charged spherical shell with surface charge density σ, and radius R. (I) σ/ε0
(B) Electric field at distance r>0 from a uniformly charged infinite plane sheet with surface charge density σ. (II) σ/2ε0
(C) Electric field outside (distance r>0 from center) of a uniformly charged spherical shell with surface charge density σ, and radius R. (III) 0
(D) Electric field between 2 oppositely charged infinite plane parallel sheets with uniform surface charge density σ. (IV) $\frac{\sigma}{\epsilon_0 r^2}$

Choose the correct answer from the options given below :

A

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

B

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

C

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

D

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

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JEE Main 2025 (Online) 28th January Morning Shift
MCQ (Single Correct Answer)
+4
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Three infinitely long wires with linear charge density $\lambda$ are placed along the $x-a x i s, y-a x i s$ and $z-$ axis respectively. Which of the following denotes an equipotential surface?

A
$\left(x^2+y^2\right)\left(y^2+z^2\right)\left(z^2+x^2\right)=$ constant
B
$x y z=$ constant
C
$x y+y z+z x=$ constant
D
$(x+y)(y+z)(z+x)=$ constant
4
JEE Main 2025 (Online) 28th January Morning Shift
MCQ (Single Correct Answer)
+4
-1
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A particle of mass ' $m$ ' and charge ' $q$ ' is fastened to one end ' $A$ ' of a massless string having equilibrium length $l$, whose other end is fixed at point ' $O$ '. The whole system is placed on a frictionless horizontal plane and is initially at rest. If uniform electric field is switched on along the direction as shown in figure, then the speed of the particle when it crosses the $x$-axis is

JEE Main 2025 (Online) 28th January Morning Shift Physics - Electrostatics Question 20 English

A
$\sqrt{\frac{\mathrm{qE} l}{2 \mathrm{~m}}}$
B
$\sqrt{\frac{\mathrm{qE} l}{4 \mathrm{~m}}}$
C
$\sqrt{\frac{\mathrm{qE} l}{\mathrm{~m}}}$
D
$\sqrt{\frac{2 \mathrm{qE} l}{\mathrm{~m}}}$
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