1
JEE Main 2019 (Online) 12th April Evening Slot
+4
-1
Consider the LR circuit shown in the figure. If the switch S is closed at t = 0 then the amount of charge that passes through the battery between t = 0 and t = $${L \over R}$$ is :
A
$${{2.7EL} \over {{R^2}}}$$
B
$${{EL} \over {2.7{R^2}}}$$
C
$${{7.3EL} \over {{R^2}}}$$
D
$${{EL} \over {7.3{R^2}}}$$
2
JEE Main 2019 (Online) 12th April Evening Slot
+4
-1
A plane electromagnetic wave having a frequency v = 23.9 GHz propagates along the positive z-direction in free space. The peak value of the Electric Field is 60 V/m. Which among the following is the acceptable magnetic field component in the electromagnetic wave ?
A
$$\overrightarrow B$$ = 2 × 10–7 sin(1.5 × 102 x + 0.5 × 1011t) $$\widehat j$$
B
$$\overrightarrow B$$ = 60 sin(0.5 × 103x + 0.5 × 1011t) $$\widehat k$$
C
$$\overrightarrow B$$ = 2 × 10–7 sin(0.5 × 103 z + 1.5 × 1011t) $$\widehat i$$
D
$$\overrightarrow B$$ = 2 × 10–7 sin(0.5 × 103 z - 1.5 × 1011t) $$\widehat i$$
3
JEE Main 2019 (Online) 10th April Evening Slot
+4
-1
A coil of self inductance 10 mH and resistance 0.1 $$\Omega$$ is connected through a switch to a battery of internal resistance 0.9 $$\Omega$$. After the switch is closed, the time taken for the current to attain 80% of the saturation value is: [take ln 5 = 1.6]
A
0.324 s
B
0.002 s
C
0.103 s
D
0.016 s
4
JEE Main 2019 (Online) 10th April Morning Slot
+4
-1
The electric field of a plane electromagnetic wave is given by
$$\overrightarrow E = {E_0}\widehat i\cos (kz)cos(\omega t)$$
The corresponding magnetic field $$\overrightarrow B$$ is then given by
A
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\sin (kz)\sin (\omega t)$$
B
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\sin (kz)\cos (\omega t)$$
C
$$\overrightarrow B = {{{E_0}} \over C}\widehat j\cos (kz)\sin (\omega t)$$
D
$$\overrightarrow B = {{{E_0}} \over C}\widehat k\sin (kz)\cos (\omega t)$$
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Physics
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Optics
Modern Physics
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