1
JEE Main 2019 (Online) 11th January Morning Slot
+4
-1
In an experiment, electrons are accelerated, from rest, by applying a voltage of 500 V. Calculate the radius of the path if a magnetic field 100 mT is then applied. [Charge of the electron = 1.6 $$\times$$ 10–19 C Mass of the electron = 9.1 $$\times$$ 10–31 kg]
A
7.5 $$\times$$ 10$$-$$4 m
B
7.5 $$\times$$ 10$$-$$3 m
C
7.5 m
D
7.5 $$\times$$ 10$$-$$2 m
2
JEE Main 2019 (Online) 11th January Morning Slot
+4
-1
There are two long co-axial solenoids of same length $$l$$. The inner and outer coils have radii r1 and r2 and number of turns per unit length n1 and n2, respectively. The ratio of mutual inductance to the self - inductance of the inner-coil is :
A
$${{{n_2}} \over {{n_1}}}.{{{r_2}^2} \over {{r_1}^2}}$$
B
$${{{n_2}} \over {{n_1}}}$$
C
$${{{n_1}} \over {{n_2}}}$$
D
$${{{n_2}} \over {{n_1}}}.{{{r_1}} \over {{r_2}}}$$
3
JEE Main 2019 (Online) 10th January Evening Slot
+4
-1
At some location on earth the horizontal component of earth’s magnetic field is 18 × 10–6 T. At this location, magnetic needle of length 0.12 m and pole strength 1.8 Am is suspended from its mid-point using a thread, it makes 45o angle with horizontal in equilibrium. To keep this needle horizontal, the vertical force that should be applied at one of its ends is -
A
3.6 $$\times$$ 10$$-$$5 N
B
1.8 $$\times$$ 10$$-$$5 N
C
1.3 $$\times$$ 10$$-$$5 N
D
6.5 $$\times$$ 10$$-$$5 N
4
JEE Main 2019 (Online) 10th January Evening Slot
+4
-1
A hoop and a solid cylinder of same mass and radius are made of a permanent magnetic material with their magnetic moment parallel to their respective axes. But the magnetic moment of hoop is twice of solid cylinder. They are placed in a uniform magnetic field in such a manner that their magnetic moments make a small angle with the field. If the oscillation periods of hoop and cylinder are Th and Tc respectively, then -
A
Th = 1.5 Tc
B
Th = Tc
C
Th = 2Tc
D
Th = 0.5 Tc
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Physics
Mechanics
Electricity
Optics
Modern Physics
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