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
A charged particle carrying charge 1 $$\mu$$C is moving
with velocity $$\left( {2\widehat i + 3\widehat j + 4\widehat k} \right)$$ ms–1. If an external
magnetic field of $$\left( {5\widehat i + 3\widehat j - 6\widehat k} \right)$$× 10–3 T exists in the region where the particle is moving then the
force on the particle is $$\overrightarrow F$$ × 10–9 N. The vector $$\overrightarrow F$$ is :
A
$${ - 0.30\widehat i + 0.32\widehat j - 0.09\widehat k}$$
B
$${ - 300\widehat i + 320\widehat j - 90\widehat k}$$
C
$${ - 30\widehat i + 32\widehat j - 9\widehat k}$$
D
$${ - 3.0\widehat i + 3.2\widehat j - 0.9\widehat k}$$
3
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
4
JEE Main 2020 (Online) 3rd September Morning Slot
+4
-1
Magnitude of magnetic field (in SI units) at the centre of a hexagonal shape coil of side 10 cm, 50 turns and carrying current I (Ampere) in units of $${{{\mu _0}I} \over \pi }$$ is :
A
250$$\sqrt 3$$
B
5$$\sqrt 3$$
C
500$$\sqrt 3$$
D
50$$\sqrt 3$$
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