1
WB JEE 2022
MCQ (Single Correct Answer)
+1
-0.25
Change Language

An electron revolves around the nucleus in a circular path with angular momentum $$\overrightarrow L $$. A uniform magnetic field $$\overrightarrow B $$ is applied perpendicular to the plane of its orbit. If the electron experiences a torque $$\overrightarrow T $$, then

A
$$\overrightarrow T ||\overrightarrow L $$
B
$$\overrightarrow T $$ is anti-parallel to $$\overrightarrow L $$
C
$$\overrightarrow T \,.\,\overrightarrow L = 0$$
D
Angle between $$\overrightarrow T $$ and $$\overrightarrow L $$ is $$45^\circ $$
2
WB JEE 2022
MCQ (Single Correct Answer)
+1
-0.25
Change Language

A straight wire is placed in a magnetic field that varies with distance x from origin as $$\overrightarrow B = {B_0}\left( {2 - {x \over a}} \right)\widehat k$$. Ends of wire are at (a, 0) and (2a, 0) and it carries a current I. If force on wire is $$\overrightarrow F = I{B_0}\left( {{{ka} \over 2}} \right)\widehat j$$, then value of k is

A
1
B
5
C
$$-$$1
D
$${1 \over 2}$$
3
WB JEE 2022
MCQ (Single Correct Answer)
+2
-0.5
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A horizontal semi-circular wire of radius r is connected to a battery through two similar springs X and Y to an electric cell, which sends current I through it. A vertically downward uniform magnetic field B is applied on the wire, as shown in the figure. What is the force acting on each spring?

WB JEE 2022 Physics - Magnetism Question 9 English

A
$$2\pi rBI$$
B
$${1 \over 2}\pi rBI$$
C
$$BIr$$
D
$$2BIr$$
4
WB JEE 2021
MCQ (Single Correct Answer)
+1
-0.25
Change Language
WB JEE 2021 Physics - Magnetism Question 12 English
Consider two infinitely long wires parallel to Z-axis carrying same current I in the positive z-direction. One wire passes through the point L at coordinates ($$-$$1, +1) and the other wire passes through the point M at coordinates ($$-$$1, $$-$$1). The resultant magnetic field at the origin O will be
A
$${{{\mu _0}I} \over {2\sqrt 2 \pi }}\widehat j$$
B
$${{{\mu _0}I} \over {2\pi }}\widehat j$$
C
$${{{\mu _0}I} \over {2\sqrt 2 \pi }}\widehat i$$
D
$${{{\mu _0}I} \over {4\pi }}\widehat i$$
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