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) 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
3
JEE Main 2019 (Online) 10th January Morning Slot
+4
-1
An insulating thin rod of length $$l$$ has a linear charge density $$\rho \left( x \right)$$ = $${\rho _0}{x \over l}$$ on it. The rod is rotated about an axis passing through the origin (x = 0) and perpendicular to the rod. If the rod makes n rotations per second, then the time averaged magnetic moment of the rod is -
A
$${\pi \over 3}n\rho {l^3}$$
B
$${\pi \over 4}n\rho {l^3}$$
C
$$n\rho {l^3}$$
D
$$\pi n\rho {l^3}$$
4
JEE Main 2019 (Online) 9th January Evening Slot
+4
-1
A particle having the same charge as of electron moves in a ciurcular path of radius 0.5 cm under the influence of a magnetic field 0f 0.5 T. If an electric field of 100 V/m makes it to move in a straight path, then the mass of the particle is (Given charge of electron = 1.6 $$\times$$ 10$$-$$19C)
A
9.1 $$\times$$ 10$$-$$31 kg
B
1.6 $$\times$$ 10$$-$$27 kg
C
1.6 $$\times$$ 10$$-$$19 kg
D
2.0 $$\times$$ 10$$-$$24 kg
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