1
JEE Main 2020 (Online) 3rd September Morning Slot
+4
-1
An elliptical loop having resistance R, of semi major axis a, and semi minor axis b is placed in magnetic field as shown in the figure. If the loop is rotated about the x-axis with angular frequency $$\omega$$, the average power loss in the loop due to Joule heating is :
A
$${{\pi abB\omega } \over R}$$
B
$${{{\pi ^2}{a^2}{b^2}{B^2}{\omega ^2}} \over R}$$
C
$${{{\pi ^2}{a^2}{b^2}{B^2}{\omega ^2}} \over {2R}}$$
D
Zero
2
JEE Main 2020 (Online) 8th January Evening Slot
+4
-1
A shown in the figure, a battery of emf $$\varepsilon$$ is connected to an inductor L and resistance R in series. The switch is closed at t = 0. The total charge that flows from the battery, between t = 0 and t = tc (tc is the time constant of the circuit) is :
A
$${{\varepsilon L} \over {e{R^2}}}$$
B
$${{\varepsilon L} \over {{R^2}}}$$
C
$${{\varepsilon L} \over {{R^2}}}\left( {1 - {1 \over e}} \right)$$
D
$${{\varepsilon R} \over {e{L^2}}}$$
3
JEE Main 2020 (Online) 8th January Morning Slot
+4
-1
At time t = 0 magnetic field of 1000 Gauss is passing perpendicularly through the area defined by the closed loop shown in the figure. If the magnetic field reduces linearly to 500 Gauss, in the next 5s, then induced EMF in the loop is :
A
48 μV
B
28 μV
C
56 μV
D
36 μV
4
JEE Main 2020 (Online) 7th January Evening Slot
+4
-1
A planar loop of wire rotates in a uniform magnetic field. Initially at t = 0, the plane of the loop is perpendicular to the magnetic field. If it rotates with a period of 10 s about an axis in its plane then the magnitude of induced emf will be maximum and minimum, respectively at :
A
2.5 s and 7.5 s
B
5.0 s and 10.0 s
C
5.0 s and 7.5 s
D
2.5 s and 5.0 s
EXAM MAP
Medical
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