1
JEE Main 2019 (Online) 12th April Morning Slot
+4
-1
A thin ring of 10 cm radius carries a uniformly distributed charge. The ring rotates at a constant angular speed of 40 $$\pi$$ rad s–1 about its axis, perpendicular to its plane. If the magnetic field at its centre is 3.8 × 10–9 T, then the charge carried by the ring is close to ($$\mu$$0 = 4$$\pi$$ × 10–7 N/A2 ).
A
7 × 10–6 C
B
4 × 10–5 C
C
2 × 10–6 C
D
3 × 10–5 C
2
JEE Main 2019 (Online) 12th April Morning Slot
+4
-1
The figure shows a square loop L of side 5 cm which is connected to a network of resistances. The whole setup is moving towards right with a constant speed of 1 cm s-1. At some instant, a part of L is in a uniform magnetic field of 1 T, perpendicular to the plane of the loop. If the resistance of L is 1.7 $$\Omega$$, the current in the loop at that instant will be close to :
A
115 $$\mu$$A
B
170 $$\mu$$A
C
60 $$\mu$$A
D
150 $$\mu$$A
3
JEE Main 2019 (Online) 12th April Morning Slot
+4
-1
An electromagnetic wave is represented by the electric field $$\overrightarrow E = {E_0}\widehat n\sin \left[ {\omega t + \left( {6y - 8z} \right)} \right]$$ . Taking unit vectors in x, y and z directions to be $$\widehat i,\widehat j,\widehat k$$ , the direction of propagation $$\widehat s$$, is :
A
$$\widehat s = {{3\widehat i - 4\widehat j} \over 5}$$
B
$$\widehat s = {{ - 4\widehat k + 3\widehat j} \over 5}$$
C
$$\widehat s = \left( {{{ - 3\widehat j + 4\widehat k} \over 5}} \right)$$
D
$$\widehat s = {{4\widehat j - 3\widehat k} \over 5}$$
4
JEE Main 2019 (Online) 12th April Morning Slot
+4
-1
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
JEE Main Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
Coordinate Geometry
Calculus
EXAM MAP
Joint Entrance Examination