1
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

A uniform but time varying magnetic field is present in a circular region of radius ' $R$ '. The magnetic field is perpendicular and into the plane of loop and the magnitude of field is increasing at a constant rate $\alpha$. There is a straight conducting rod of length 2 R placed as shown in figure. The magnitude of induced emf across the rod is

WB JEE 2026 Physics - Electromagnetic Induction Question 1 English

A

$\pi \mathrm{R}^2 \alpha$

B

$\frac{1}{2} \pi \mathrm{R}^2 \alpha$

C

$\frac{1}{\sqrt{2}} \mathrm{R}^2 \alpha$

D

$\frac{1}{4} \pi \mathrm{R}^2 \alpha$

2
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

From a tower of height $H$ ,a particle is thrown vertically upwards with a speed $u$ .The time taken by the particle to hit the ground is $n$ times that taken by it to reach the highest point of its path.The relation between $H, u$ and $n$ is

A

$2 g H=n^2 u^2$

B

$g H=(n-2)^2 u^2$

C

$2 g H=n u^2(n-2)$

D

$2 g H=u^2(n-2)^2$

3
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

There is a ring of radius $r$ having linear charge density $\lambda$ and rotating with a uniform angular velocity $\omega$. The magnitude of the magnetic field produced by this ring at its own centre would be ( $\mu_0=$ permeability of air)

A

$\frac{\lambda \omega^2}{2-\mu_0}$

B

$\frac{\mu_0 \lambda^2 \omega}{\sqrt{2}}$

C

$\frac{\mu_0 \lambda \omega}{2}$

D

$\frac{\mu_0 \lambda}{2 \omega^2}$

4
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

Three vectors $\vec{a}, \vec{b}$ and $\vec{c}$ are such that $|\vec{a}|=1,|\vec{b}|=2$ and $|\vec{c}|=4$ along with $\vec{a}+\vec{b}+\vec{c}=0$ .Then,the value of $4 \vec{a} \cdot \vec{b}+3 \vec{b} \cdot \vec{c}+3 \vec{c} \cdot \vec{a}$ will be

A

27

B

-26

C

-68 problem is wrong.

D

-34