JEE Main 2019 (Online) 10th January Evening Slot | Electromagnetic Waves Question 120 | Physics

JEE Main 2019 (Online) 10th January Evening Slot

MCQ (Single Correct Answer)

-1

The electric field of a plane polarized electromagnetic wave in free space at time t = 0 is given by an expression $$\overrightarrow E \left( {x,y} \right) = 10\widehat j\cos \left[ {\left( {6x + 8z} \right)} \right].$$ The magnetic field $$\overrightarrow B $$(x,z, t) is given by $$-$$ (c is the velocity of light)

$${1 \over c}\left( {6\hat k + 8\widehat i} \right)\cos \left[ {\left( {6x + 8z - 10ct} \right)} \right]$$

$${1 \over c}\left( {6\widehat k - 8\widehat i} \right)\cos \left[ {\left( {6x + 8z - 10ct} \right)} \right]$$

$${1 \over c}\left( {6\hat k + 8\widehat i} \right)\cos \left[ {\left( {6x - 8z + 10ct} \right)} \right]$$

$${1 \over c}\left( {6\hat k - 8\widehat i} \right)\cos \left[ {\left( {6x - 8z + 10ct} \right)} \right]$$

JEE Main 2019 (Online) 10th January Morning Slot

MCQ (Single Correct Answer)

-1

If the magnetic field of a plane electromagnetic wave is given by (the speed of light = 3 × 10⁸ B = 100 × 10^–6 sin $$\left[ {2\pi \times 2 \times {{10}^{15}}\left( {t - {x \over c}} \right)} \right]$$ then the maximum electric field associated with it is -

4.5 $$ \times $$ 10⁴ N/C

4 $$ \times $$ 10⁴ N/C

6 $$ \times $$ 10⁴ N/C

3 $$ \times $$ 10⁴ N/C

JEE Main 2019 (Online) 9th January Evening Slot

MCQ (Single Correct Answer)

-1

The energy associated with electric field is (U_E) and with magnetic field is (U_B) for an electromagnetic wave in free space. Then :

$${U_E} = {{{U_B}} \over 2}$$

$${U_E} > {U_B}$$

$${U_E} < {U_B}$$

$${U_E} = {U_B}$$

JEE Main 2019 (Online) 9th January Morning Slot

MCQ (Single Correct Answer)

-1

A plane electromagnetic wave of frequency 50 MHz travels in free space along the positive x-direction. At a particular point in space and time, $$\overrightarrow E = 6.3\widehat j\,V/m.$$ The corresponding magnetic field $$\overrightarrow {B,} $$ at that point will be :

18.9 $$ \times $$ 10^$$-$$8 $$\widehat k$$T

2.1 $$ \times $$ 10^$$-$$8 $$\widehat k$$T

6.3 $$ \times $$ 10^$$-$$8 $$\widehat k$$T

18.9 $$ \times $$ 10⁸ $$\widehat k$$T

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