JEE MainPhysicsElectromagnetic Waves
For an electromagnetic wave propagating in a vacuum, let B , k , and represent the magnetic field vector, propagation vector, and angular frequency, respectively. If c is the speed of light in vacuum, the electric field vector E of the wave can be expressed as :
Options
- Ac^2 ( k B )
- B1 ( B k )
- Cc^2 ( B k )
- Dc^2 ( B k )
Correct answer
D. c^2 ( B k )
Step-by-step solution
For an electromagnetic wave, the direction of wave propagation is given by k = E B . Since E , B , and k form a mutually perpendicular right-handed system, the direction of the electric field is E = B k . The magnitudes of the electric and magnetic fields are related by E = cB . The speed of light is related to the angular frequency and wave number by c = k , which gives k = c . Combining the magnitude and direction, we write the electric field vector as: E = E E = cB( B k ) Multiplying and dividing by k , we get: