1
JEE Main 2020 (Online) 3rd September Morning Slot
+4
-1
The magnetic field of a plane electromagnetic wave is
$$\overrightarrow B = 3 \times {10^{ - 8}}\sin \left[ {200\pi \left( {y + ct} \right)} \right]\widehat i$$ T
where c = 3 $$\times$$ 108 ms–1 is the speed of light. The corresponding electric field is :
A
$$\overrightarrow E = - {10^{ - 6}}\sin \left[ {200\pi \left( {y + ct} \right)} \right]\widehat k$$ V/m
B
$$\overrightarrow E = - 9\sin \left[ {200\pi \left( {y + ct} \right)} \right]\widehat k$$ V/m
C
$$\overrightarrow E = 9\sin \left[ {200\pi \left( {y + ct} \right)} \right]\widehat k$$ V/m
D
$$\overrightarrow E = 3 \times {10^{ - 8}}\sin \left[ {200\pi \left( {y + ct} \right)} \right]\widehat k$$
2
JEE Main 2020 (Online) 3rd September Morning Slot
+4
-1
A 750 Hz, 20 V (rms) source is connected to a resistance of 100 $$\Omega$$, an inductance of 0.1803 H and a capacitance of 10 $$\mu$$F all in series. The time in which the resistance (heat capacity 2 J/oC) will get heated by 10oC. (assume no loss of heat to the surroudnings) is close to :
A
348 s
B
418 s
C
245 s
D
365 s
3
JEE Main 2020 (Online) 2nd September Evening Slot
+4
-1
In a plane electromagnetic wave, the directions of electric field and magnetic field are represented by $$\widehat k$$ and $$2\widehat i - 2\widehat j$$, respectively. What is the unit vector along direction of propagation of the wave?
A
$${1 \over {\sqrt 5 }}\left( {\widehat i + 2\widehat j} \right)$$
B
$${1 \over {\sqrt 5 }}\left( {2\widehat i + \widehat j} \right)$$
C
$${1 \over {\sqrt 2 }}\left( {\widehat i + \widehat j} \right)$$
D
$${1 \over {\sqrt 2 }}\left( {\widehat j + \widehat k} \right)$$
4
JEE Main 2020 (Online) 2nd September Evening Slot
+4
-1
An inductance coil has a reactance of 100 $$\Omega$$. When an AC signal of frequency 1000 Hz is applied to the coil, the applied voltage leads the current by 45o. The self-inductance of the coil is
A
6.7 $$\times$$ 10–7 H
B
1.1 $$\times$$ 10–1 H
C
5.5 $$\times$$ 10–5 H
D
1.1 $$\times$$ 10–2 H
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