1
JEE Main 2019 (Online) 10th April Evening Slot
MCQ (Single Correct Answer)
+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
MCQ (Single Correct Answer)
+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
MCQ (Single Correct Answer)
+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
4
JEE Main 2019 (Online) 9th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Two coils 'P' and 'Q' are separated by some distance. When a current of 3 A flows through coil 'P', a magnetic flux of 10–3 Wb passes through 'Q'. No current is passed through 'Q'. When no current passes through 'P' and a current of 2 A passes through 'Q', the flux through 'P' is :-
A
3.67 × 10–4 Wb
B
3.67 × 10–3 Wb
C
6.67 × 10–4 Wb
D
6.67 × 10–3 Wb
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