1
JEE Main 2022 (Online) 30th June Morning Shift
+4
-1

A coil of n number of turns wound tightly in the form of a spiral with inner and outer radii r1 and r2 respectively. When a current of strength I is passed through the coil, the magnetic field at its centre will be :

A
$${{{\mu _0}nI} \over {2({r_2} - {r_1})}}$$
B
$${{{\mu _0}nI} \over {{r_2}}}$$
C
$${{{\mu _0}nI} \over {{r_2} - {r_1}}}{\log _e}{{{r_1}} \over {{r_2}}}$$
D
$${{{\mu _0}nI} \over {2({r_2} - {r_1})}}{\log _e}{{{r_2}} \over {{r_1}}}$$
2
JEE Main 2022 (Online) 29th June Evening Shift
+4
-1 Two long current carrying conductors are placed to each other at a distance of 8 cm between them. The magnitude of magnetic field produced at mid-point between the two conductors due to current flowing in them is 300 $$\mu$$T. The equal current flowing in the two conductors is :

A
30A in the same direction.
B
30A in the opposite direction.
C
60A in the opposite direction.
D
300A in the opposite direction.
3
JEE Main 2022 (Online) 29th June Evening Shift
+4
-1 Given below are two statements :

Statement I : The electric force changes the speed of the charged particle and hence changes its kinetic energy; whereas the magnetic force does not change the kinetic energy of the charged particle.

Statement II : The electric force accelerates the positively charged particle perpendicular to the direction of electric field. The magnetic force accelerates the moving charged particle along the direction of magnetic field.

In the light of the above statements, choose the most appropriate answer from the options given below :

A
Both Statement I and Statement II are correct.
B
Both Statement I and Statement II are incorrect.
C
Statement I is correct but Statement II is incorrect.
D
Statement I is incorrect but Statement II is correct.
4
JEE Main 2022 (Online) 29th June Morning Shift
+4
-1 A charge particle moves along circular path in a uniform magnetic field in a cyclotron. The kinetic energy of the charge particle increases to 4 times its initial value. What will be the ratio of new radius to the original radius of circular path of the charge particle :

A
1 : 1
B
1 : 2
C
2 : 1
D
1 : 4
JEE Main Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
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