1
JEE Main 2019 (Online) 10th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Two wires A & B are carrying currents I1 & I2 as shown in the figure. The separation between them is d. A third wire C carrying a current I is to be kept parallel to them at a distance x from A such that the net force acting on it is zero. The possible values of x are : JEE Main 2019 (Online) 10th April Morning Slot Physics - Magnetic Effect of Current Question 160 English
A
$$x = \left( {{{{I_1}} \over {{I_1} + {I_2}}}} \right)d\,and\,x = \left( {{{{I_2}} \over {{I_1} - {I_2}}}} \right)d$$
B
$$x = \left( {{{{I_2}} \over {{I_1} + {I_2}}}} \right)d\,and\,x = \left( {{{{I_2}} \over {{I_1} - {I_2}}}} \right)d$$
C
$$x = \left( {{{{I_1}} \over {{I_1} - {I_2}}}} \right)d\,and\,x = \left( {{{{I_2}} \over {{I_1} + {I_2}}}} \right)d$$
D
$$x = \pm {{{I_1}d} \over {{I_1} - {I_2}}}$$
2
JEE Main 2019 (Online) 10th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A particle of mass m is moving along a trajectory given by
x = x0 + a cos$$\omega $$1t
y = y0 + b sin$$\omega $$2t
The torque, acting on the particle about the origin, at t = 0 is :
A
Zero
B
+my0a $$\omega _1^2$$$$\widehat k$$
C
$$ - m\left( {{x_0}b\omega _2^2 - {y_0}a\omega _1^2} \right)\widehat k$$
D
m (–x0b + y0a) $$\omega _1^2$$$$\widehat k$$
3
JEE Main 2019 (Online) 10th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The electric field of a plane electromagnetic wave is given by
$$\overrightarrow E = {E_0}\widehat i\cos (kz)cos(\omega t)$$
The corresponding magnetic field $$\overrightarrow B $$ is then given by
A
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\sin (kz)\sin (\omega t)$$
B
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\sin (kz)\cos (\omega t)$$
C
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\cos (kz)\sin (\omega t)$$
D
$$\overrightarrow B = {{{E_0}} \over C}\widehat k\sin (kz)\cos (\omega t)$$
4
JEE Main 2019 (Online) 10th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Two coaxial discs, having moments of inertia I1 and I1/2, are rotating with respective angular velocities $$\omega $$1 and $$\omega $$1/2 , about their common axis. They are brought in contact with each other and thereafter they rotate with a common angular velocity. If Ef and Ei are the final and initial total energies, then (Ef - Ei) is:
A
$${{{I_1}\omega _1^2} \over {24}}$$
B
$${{{I_1}\omega _1^2} \over {12}}$$
C
$${3 \over 8}{I_1}\omega _1^2$$
D
$${{{I_1}\omega _1^2} \over {6}}$$
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