1
JEE Main 2022 (Online) 28th July Morning Shift
+4
-1 The current sensitivity of a galvanometer can be increased by :

(A) decreasing the number of turns

(B) increasing the magnetic field

(C) decreasing the area of the coil

(D) decreasing the torsional constant of the spring

Choose the most appropriate answer from the options given below :

A
(B) and (C) only
B
(C) and (D) only
C
(A) and (C) only
D
(B) and (D) only
2
JEE Main 2022 (Online) 28th July Morning Shift
+4
-1 As shown in the figure, a metallic rod of linear density $$0.45 \mathrm{~kg} \mathrm{~m}^{-1}$$ is lying horizontally on a smooth inclined plane which makes an angle of $$45^{\circ}$$ with the horizontal. The minimum current flowing in the rod required to keep it stationary, when $$0.15 \mathrm{~T}$$ magnetic field is acting on it in the vertical upward direction, will be :

{Use $$g=10 \mathrm{~m} / \mathrm{s}^{2}$$} A
30 A
B
15 A
C
10 A
D
3 A
3
JEE Main 2022 (Online) 27th July Evening Shift
+4
-1 A compass needle of oscillation magnetometer oscillates 20 times per minute at a place $$\mathrm{P}$$ of $$\operatorname{dip} 30^{\circ}$$. The number of oscillations per minute become 10 at another place $$\mathrm{Q}$$ of $$60^{\circ}$$ dip. The ratio of the total magnetic field at the two places $$\left(B_{Q}: B_{P}\right)$$ is :

A
$$\sqrt{3}: 4$$
B
$$4: \sqrt{3}$$
C
$$\sqrt{3}: 2$$
D
$$2: \sqrt{3}$$
4
JEE Main 2022 (Online) 27th July Evening Shift
+4
-1 A cyclotron is used to accelerate protons. If the operating magnetic field is $$1.0 \mathrm{~T}$$ and the radius of the cyclotron 'dees' is $$60 \mathrm{~cm}$$, the kinetic energy of the accelerated protons in MeV will be :

$$[\mathrm{use} \,\,\mathrm{m}_{\mathrm{p}}=1.6 \times 10^{-27} \mathrm{~kg}, \mathrm{e}=1.6 \times 10^{-19} \,\mathrm{C}$$ ]

A
12
B
18
C
16
D
32
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