1
JEE Main 2021 (Online) 26th August Morning Shift
MCQ (Single Correct Answer)
+4
-1
An inductor coil stores 64 J of magnetic field energy and dissipates energy at the rate of 640 W when a current of 8A is passed through it. If this coil is joined across an ideal battery, find the time constant of the circuit in seconds :
A
0.4
B
0.8
C
0.125
D
0.2
2
JEE Main 2021 (Online) 20th July Morning Shift
MCQ (Single Correct Answer)
+4
-1
The arm PQ of a rectangular conductor is moving from x = 0 to x = 2b outwards and then inwards from x = 2b to x = 0 as shown in the figure. A uniform magnetic field perpendicular to the plane is acting from x = 0 to x = b. Identify the graph showing the variation of different quantities with distance.

A
A-Flux, B-Power dissipated, C-EMF
B
A-Flux, B-EMF, C-Power dissipated
C
A-Power dissipated, B-Flux, C-EMF
D
A-EMF, B-Power dissipated, C-Flux
3
JEE Main 2021 (Online) 18th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
The time taken for the magnetic energy to reach 25% of its maximum value, when a solenoid of resistance R, inductance L is connected to a battery, is :
A
infinite
B
$${L \over R}$$ ln10
C
$${L \over R}$$ ln2
D
$${L \over R}$$ ln5
4
JEE Main 2021 (Online) 16th March Evening Shift
MCQ (Single Correct Answer)
+4
-1
The magnetic field in a region is given by $$\overrightarrow B = {B_o}\left( {{x \over a}} \right)\widehat k$$. A square loop of side d is placed with its edges along the x and y axes. The loop is moved with a constant velocity $$\overrightarrow v$$ = v0$$\widehat i$$. The emf induced in the loop is :

A
$${{{B_o}{v_o}{d^2}} \over {2a}}$$
B
$${{{B_o}v_o^2d} \over {2a}}$$
C
$${{{B_o}{v_o}d} \over {2a}}$$
D
$${{{B_o}{v_o}{d^2}} \over a}$$
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