Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 20203 SeptemberEvening Shift
Exam
JEE Main
Year
2020
Date
3 September
Shift
Evening Shift
Subject
Physics
Chapter
Electromagnetic Waves

JEE Main 2020 · 3 September · Evening Shift · Physics · Electromagnetic Waves

The electric field of a plane electromagnetic wave propagating...

The electric field of a plane electromagnetic wave propagating along the x direction in vacuum is E→=E0jcos(\omegat−kx).\overset{\to}{E} = {E}_{0}jcos ( \omegat - kx ) . The magnetic field B→,\overset{\to}{B}, at the moment t=0t = 0 is:

Options

  1. A\overset{\to}{B} = \dfrac{{E}_{0}}{\sqrt{{\mu}_{0}{ϵ}_{0}}}\cos ( kx ) \overset{^}{k}
  2. B\overset{\to}{B} = {E}_{0}\sqrt{{\mu}_{0}{ϵ}_{0}}\cos ( kx ) \overset{^}{j}
  3. C\overset{\to}{B} = {E}_{0}\sqrt{{\mu}_{0}{ε}_{0}}\cos ( kx ) \overset{^}{k}
  4. D\overset{\to}{B} = \dfrac{{E}_{0}}{\sqrt{{\mu}_{0}{ϵ}_{0}}}\cos ( kx ) \overset{^}{j}

Correct answer

C. \overset{\to}{B} = {E}_{0}\sqrt{{\mu}_{0}{ε}_{0}}\cos ( kx ) \overset{^}{k}

Step-by-step solution

B0=E0C=E01/μ0ε0=E0μ0ε0{B}_{0} = \dfrac{{E}_{0}}{C} = \dfrac{{E}_{0}}{1 / \sqrt{{\mu}_{0}{ε}_{0}}} = {E}_{0}\sqrt{{\mu}_{0}{ε}_{0}}

As the light is propagating in xx direction

and \overset{^}{E} \times \overset{^}{B} | | \overset{^}{C}

∴∴ B→\overset{\to}{B} should be in \overset{^}{K} direction

Practice Electromagnetic Waves on Quantrex Academy →

More from Electromagnetic Waves

The electric field associated with an electromagnetic wave travelling in vacuum is given… JEE Advanced 2026A monochromatic source of light operating at 15 kW emits 2.5× 10^ 22 photons/s. The… JEE Main 2026For an electromagnetic wave propagating through vacuum, k , E and ω represent propagation… JEE Main 2026A point light source emits E.M. waves in free space. A detector, placed at a distance of… JEE Main 2026A displacement current of 4.0 A can be set up in the space between two parallel plates of… JEE Main 2026A magnetic field vector in an electromagnetic wave is represented by B =B_0 (2π vt-(2π… JEE Main 2026An electromagnetic wave travels in free space along the x -direction. At a particular… JEE Main 2026An electromagnetic wave travelling in x -direction is described by field equation E_y =… JEE Main 2026 Full Electromagnetic Waves list All JEE Main PYQs