1
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
Consider a circular coil of wire carrying constant current I, forming a magnetic dipole. The magnetic flux through an infinite plane that contains the circular coil and excluding the circular coil area is given by $$\phi $$i. The magnetic flux through the area of the circular coil area is given by $$\phi $$0. Which of the following option is correct?
A
$$\phi $$i = $$\phi $$0
B
$$\phi $$i < $$\phi $$0
C
$$\phi $$i $$>$$ $$\phi $$0
D
$$\phi $$i = - $$\phi $$0
2
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A polarizer - analyser set is adjusted such that the intensity of light coming out of the analyser is just 10% of the original intensity. Assuming that the polarizer - analyser set does not absorb any light, the angle by which the analyser need to be rotated further to reduce the output intensity to be zero, is :
A
71.6o
B
90o
C
18.4o
D
45o
3
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The radius of gyration of a uniform rod of length $$l$$, about an axis passing through a point $${l \over 4}$$ away from the centre of the rod, and perpendicular to it, is :
A
$${1 \over 8}l$$
B
$${1 \over 4}l$$
C
$$\sqrt {{7 \over {48}}} l$$
D
$$\sqrt {{3 \over 8}} l$$
4
JEE Main 2020 (Online) 7th January Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A long solenoid of radius R carries a time (t) - dependent current
I(t)=I0t(1 - t). A ring of radius 2R is placed coaxially near its middle. During the time interval 0 $$ \le $$ t $$ \le $$ 1, the induced current (IR) and the induced EMF(VR) in the ring change as :
A
Direction of IR remains unchanged and VR is zero at t = 0.25
B
Direction of IR remains unchanged and VR is maximum at t = 0.5
C
At t = 0.25 direction of IR reverses and VR is maximum
D
At t = 0.5 direction of IR reverses and VR is zero
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