1
JEE Main 2019 (Online) 10th April Evening Slot
+4
-1
A square loop is carrying a steady current I and the magnitude of its magnetic dipole moment is m. if this square loop is changed to a circular loop and it carries the same current, the magnitude of the magnetic dipole moment of circular loop will be:
A
$${m \over \pi }$$
B
$${{3m} \over \pi }$$
C
$${{2m} \over \pi }$$
D
$${{4m} \over \pi }$$
2
JEE Main 2019 (Online) 10th April Evening Slot
+4
-1
The magnitude of the magnetic field at the centre of an equilateral triangular loop of side 1 m which is carrying a current of 10 A is :
[Take $$\mu$$0 = 4$$\pi$$ × 10–7 NA–2]
A
3 $$\mu$$T
B
18 $$\mu$$T
C
9 $$\mu$$T
D
1 $$\mu$$T
3
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
$$x = \pm {{{I_1}d} \over {{I_1} - {I_2}}}$$
4
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
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