1
JEE Main 2019 (Online) 10th April Morning Slot
+4
-1
A proton, an electron, and a Helium nucleus, have the same energy. They are in circular orbits in a plane due to magnetic field perpendicualr to the plane. Let rp, re and rHe be their respective radii, then
A
re < rp < rHe
B
re < rp = rHe
C
re > rp > rHe
D
re > rp = rHe
2
JEE Main 2019 (Online) 10th April Morning Slot
+4
-1
Two wires A & B are carrying currents I1 & I2 as shown in the figure. The separation between them is d. A third wire C carrying a current I is to be kept parallel to them at a distance x from A such that the net force acting on it is zero. The possible values of x are :
A
$$x = \left( {{{{I_1}} \over {{I_1} + {I_2}}}} \right)d\,and\,x = \left( {{{{I_2}} \over {{I_1} - {I_2}}}} \right)d$$
B
$$x = \left( {{{{I_2}} \over {{I_1} + {I_2}}}} \right)d\,and\,x = \left( {{{{I_2}} \over {{I_1} - {I_2}}}} \right)d$$
C
$$x = \left( {{{{I_1}} \over {{I_1} - {I_2}}}} \right)d\,and\,x = \left( {{{{I_2}} \over {{I_1} + {I_2}}}} \right)d$$
D
$$x = \pm {{{I_1}d} \over {{I_1} - {I_2}}}$$
3
JEE Main 2019 (Online) 9th April Evening Slot
+4
-1
A moving coil galvanometer has a coil with 175 turns and area 1 cm2. It uses a torsion band of torsion constant 10–6 N-m/rad. The coil is placed in a maganetic field B parallel to its plane. The coil deflects by 1° for a current of 1 mA. The value of B (in Tesla) is approximately :-
A
10–4
B
10–2
C
10–1
D
10–3
4
JEE Main 2019 (Online) 9th April Morning Slot
+4
-1
A rigid square loop of side 'a' and carrying current I2 is lying on a horizontal surface near a long current I1 carrying wire in the same plane as shown in figure. The net force on the loop due to wire will be :
A
Repulsive and equal to $$\mu$$0I1I2/4$$\pi$$
B
Attractive and equal to $$\mu$$0I1I2/3$$\pi$$
C
Repulsive and equal to $$\mu$$0I1I2/2$$\pi$$
D
Zero
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