1
JEE Main 2020 (Online) 3rd September Evening Slot
+4
-1
A uniform magnetic field B exists in a direction perpendicular to the plane of a square loop made of a metal wire. The wire has a diameter of 4 mm and a total length of 30 cm. The magnetic field changes with time at a steady rate $${{dB} \over {dt}}$$ = 0.032 Ts–1. The induced current in the loop is close to (Resistivity of the metal wire is 1.23 $$\times$$ 10–8 $$\Omega$$m)
A
0.53 A
B
0.43 A
C
0.34 A
D
0.61 A
2
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
3
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
$${{\varepsilon R} \over {e{L^2}}}$$
4
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
EXAM MAP
Medical
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