1
WB JEE 2024
+1
-0.25

A charged particle moving with a velocity $$\vec{v}=v_1 \hat{i}+v_2 \hat{j}$$ in a magnetic field $$\vec{B}$$ experiences a force $$\vec{F}=F_1 \hat{i}+F_2 \hat{j}$$. Here $$v_1, v_2, F_1, F_2$$ all are constants. Then $$\overrightarrow{\mathrm{B}}$$ can be

A
$$\vec{B}=B_1 \hat{i}+B_2 \hat{j}$$ with $$\frac{v_1}{v_2}=\frac{B_1}{B_2}$$
B
$$\vec{B}=B_1 \hat{i}+B_2 \hat{j}+B_3 \hat{k}$$ with $$\frac{v_1}{v_2}=\frac{B_1}{B_2}$$
C
$$\overrightarrow{\mathrm{B}}=\mathrm{B}_3 \hat{\mathrm{j}}$$ with $$\mathrm{B}_1=\mathrm{B}_2=0$$
D
$$\vec{B}=B_1 \hat{j}+B_2 \hat{k}$$ with $$\frac{B_1}{B_2}=\frac{v_1}{v_2}$$
2
WB JEE 2023
+1
-0.25

A wire carrying a steady current I is kept in the x-y plane along the curve $$y=A \sin \left(\frac{2 \pi}{\lambda} x\right)$$. A magnetic field B exists in the z-direction. The magnitude of the magnetic force in the portion of the wire between x = 0 and x = $$\lambda$$ is

A
0
B
2I$$\lambda$$B
C
I$$\lambda$$B
D
I$$\lambda$$B/2
3
WB JEE 2023
+2
-0.5

A bar magnet falls from rest under gravity through the centre of a horizontal ring of conducting wire as shown in figure. Which of the following graph best represents the speed (v) vs. time (t) graph of the bar magnet?

A
B
C
D
4
WB JEE 2022
+1
-0.25

Two infinite line-charges parallel to each other are moving with a constant velocity v in the same direction as shown in the figure. The separation between two line-charges is d. The magnetic attraction balances the electric repulsion when, [ c = speed of light in free space ]

A
$$v = \sqrt 2 c$$
B
$$v = {c \over {\sqrt 2 }}$$
C
$$v = c$$
D
$$v = {c \over 2}$$
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