JEE Main202325 Jan 2023Morning ShiftPhysicsElectromagnetic WavesActual
All electromagnetic wave is transporting energy in the negative z direction. At a certain point and certain time the direction of electric field of the wave is along positive y direction. What will be the direction of the magnetic field of the wave at that point and instant?
Options
- APositive direction of x
- BPositive direction of z
- CNegative direction of x
- DNegative direction of y
Correct answer
A. Positive direction of x
Step-by-step solution
In an electromagnetic wave, the direction of energy flow is along the direction of the wave propagation. Therefore, the wave propagates along negative z direction. Electric field is along the positive y direction and the wave propagates along negative z direction. Thus, magnetic field is in direction perpendicular to both z and y axes. Using vector algebra, ( - k ^ ) = ( + j ^ ) × i ^ Hence, magnetic field is in positive x direction.