1
JEE Main 2020 (Online) 6th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A square loop of side 2$$a$$ and carrying current I is kept in xz plane with its centre at origin. A long wire carrying the same current I is placed parallel to z-axis and passing through point (0, b, 0), (b >> a). The magnitude of torque on the loop about z-axis will be :
A
$${{2{\mu _0}{I^2}{a^2}} \over {\pi b}}$$
B
$${{2{\mu _0}{I^2}{a^2}b} \over {\pi \left( {{a^2} + {b^2}} \right)}}$$
C
$${{{\mu _0}{I^2}{a^2}b} \over {2\pi \left( {{a^2} + {b^2}} \right)}}$$
D
$${{{\mu _0}{I^2}{a^2}} \over {2\pi b}}$$
2
JEE Main 2020 (Online) 6th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
An electron is moving along +x direction with a velocity of 6 $$ \times $$ 106 ms–1. It enters a region of uniform electric field of 300 V/cm pointing along +y direction. The magnitude and direction of the magnetic field set up in this region such that the electron keeps moving along the x direction will be :
A
3 $$ \times $$ 10–4 T, along –z direction
B
5 $$ \times $$ 10–3 T, along –z direction
C
5 $$ \times $$ 10–3 T, along +z direction
D
3 $$ \times $$ 10–4 T, along +z direction
3
JEE Main 2020 (Online) 6th September Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A particle of charge q and mass m is moving with a velocity $$ - v\widehat i$$ (v $$ \ne $$ 0) towards a large screen placed in the Y - Z plane at a distance d. If there is a magnetic field $$\overrightarrow B = {B_0}\widehat k$$ , the maximum value of v for which the particle will not hit the screen is :
A
$${{2qd{B_0}} \over m}$$
B
$${{qd{B_0}} \over {3m}}$$
C
$${{qd{B_0}} \over {2m}}$$
D
$${{qd{B_0}} \over {m}}$$
4
JEE Main 2020 (Online) 5th September Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
An iron rod of volume 10–3 m3 and relative permeability 1000 is placed as core in a solenoid with 10 turns/cm. If a current of 0.5 A is passed through the solenoid, then the magnetic moment of the rod will be :
A
5 $$ \times $$ 102 Am2
B
0.5 $$ \times $$ 102 Am2
C
500 $$ \times $$ 102 Am2
D
50 $$ \times $$ 102 Am2
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