JEE Main 2019 (Online) 11th January Morning Slot | Magnetics Question 197 | Physics

JEE Main 2019 (Online) 11th January Morning Slot

MCQ (Single Correct Answer)

-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]

7.5 $$ \times $$ 10^$$-$$4 m

7.5 $$ \times $$ 10^$$-$$3 m

7.5 m

7.5 $$ \times $$ 10^$$-$$2 m

JEE Main 2019 (Online) 11th January Morning Slot

MCQ (Single Correct Answer)

-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 :

$${{{n_2}} \over {{n_1}}}.{{{r_2}^2} \over {{r_1}^2}}$$

$${{{n_2}} \over {{n_1}}}$$

$${{{n_1}} \over {{n_2}}}$$

$${{{n_2}} \over {{n_1}}}.{{{r_1}} \over {{r_2}}}$$

JEE Main 2019 (Online) 10th January Evening Slot

MCQ (Single Correct Answer)

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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 45^o angle with horizontal in equilibrium. To keep this needle horizontal, the vertical force that should be applied at one of its ends is -

3.6 $$ \times $$ 10^$$-$$5 N

1.8 $$ \times $$ 10^$$-$$5 N

1.3 $$ \times $$ 10^$$-$$5 N

6.5 $$ \times $$ 10^$$-$$5 N

JEE Main 2019 (Online) 10th January Evening Slot

MCQ (Single Correct Answer)

-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 T_h and T_c respectively, then -

T_h = 1.5 T_c

T_h = T_c

T_h = 2T_c

T_h = 0.5 T_c

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