1
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
$${1 \over {\sqrt 2 }}\left( {\widehat j + \widehat k} \right)$$
2
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
3
JEE Main 2020 (Online) 2nd September Morning Slot
+4
-1
A plane electromagnetic wave, has
frequency of 2.0 $$\times$$ 1010 Hz and its energy density is 1.02 $$\times$$ 10–8 J/m3 in vacuum. The amplitude of the magnetic field of the wave is close to
( $${1 \over {4\pi {\varepsilon _0}}} = 9 \times {10^9}{{N{m^2}} \over {{C^2}}}$$ and speed of light
= 3 $$\times$$ 108 ms–1)
A
190 nT
B
150 nT
C
160 nT
D
180 nT
4
JEE Main 2020 (Online) 9th January Evening Slot
+4
-1
In LC circuit the inductance L = 40 mH and
capacitance C = 100 $$\mu$$F. If a voltage
V(t) = 10sin(314t) is applied to the circuit, the
current in the circuit is given as :
A
0.52 cos 314 t
B
5.2 cos 314 t
C
0.52 sin 314 t
D
10 cos 314 t
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