1
JEE Main 2019 (Online) 12th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Out of Syllabus
A magnetic compass needle oscillates 30 times per minute at a place where the dip is 45o, and 40 times per minute where the dip is 30o. If B1 and B2 are respectively the total magnetic field due to the earth at the two places, then the ratio $${{{B_1}} \over {{B_2}}}$$ is best given by :
A
1.8
B
2.2
C
0.7
D
3.6
2
JEE Main 2019 (Online) 8th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Two magnetic dipoles X and Y are placed at a separation d, with their axes perpendicular to each other. The dipole moment of Y is twice that of X. A particle of charge q is passing, through their midpoint P, at angle q = 45° with the horizontal line, as shown in figure. What would be the magnitude of force on the particle at that instant ?
(d is much larger than the dimensions of the dipole)
A
$$\left( {{{{\mu _0}} \over {4\pi }}} \right){2M \over {{{\left( {d/2} \right)}^3}}} \times qv$$
B
$$\left( {{{{\mu _0}} \over {4\pi }}} \right){M \over {{{\left( {d/2} \right)}^3}}} \times qv$$
C
$$\sqrt 2 \left( {{{{\mu _0}} \over {4\pi }}} \right){M \over {{{\left( {d/2} \right)}^3}}} \times qv$$
D
0
3
JEE Main 2019 (Online) 12th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
A paramagnetic material has 1028 atoms/m3. Its magnetic susceptibility at temperature 350 K is 2.8 $$\times$$ 10–4. Its susceptibility at 300 K is :
A
3.726 $$\times$$ 10–4
B
2.672 $$\times$$ 10–4
C
3.672 $$\times$$ 10–4
D
3.267 $$\times$$ 10$$-$$4
4
JEE Main 2019 (Online) 11th January Evening Slot
MCQ (Single Correct Answer)
+4
-1
A paramagnetic substance in the form of a cube with sides 1 cm has a magnetic dipole moment of 20 $$\times$$ 10–6 J/ T when a magnetic intensity of 60 $$\times$$ 103 A/m is applied. Its magnetic susceptibility is
A
3.3 $$\times$$ 10–4
B
2.3 $$\times$$ 10–2
C
4.3 $$\times$$ 10–2
D
3.3 $$\times$$ 10–2
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