JEE Main20209 Jan 2020Evening ShiftPhysicsElectromagnetic WavesActual
A plane electromagnetic wave is propagating along the direction i ^ + j ^ 2 , with its polarization along the direction k . ^ The correct form of the magnetic field of the wave would be (here B 0 is an appropriate constant):
Options
- AB 0 i ^ - j ^ 2 c o s ω t - k i ^ + j ^ 2
- BB 0 j ^ - i ^ 2 c o s ω t + k i ^ + j ^ 2
- CB 0 k ^ c o s ω t - k i ^ + j ^ 2
- DB 0 i ^ + j ^ 2 c o s ω t - k i ^ + j ^ 2
Correct answer
A. B 0 i ^ - j ^ 2 c o s ω t - k i ^ + j ^ 2
Step-by-step solution
Polarization of EM Wave means Direction of Its electric Field Electric field vector is along k ^ So, unit electric filed vector, E → = k ^ (Given) Direction of wave, c ^ = i ^ + j ^ 2 (Given) B ^ denotes unit magnetic field vector. B ^ = C ^   × E ^ B ^ = i ^ + j ^ 2 × k ^ = i ^ - j ^ 2 General Form is B = ( B 0 B ^ ) cos ω t - c ^ k where B 0 is Magnitude of Magnetic Field S o ,   B = B 0 i ^ - j ^ 2 cos ω t - k i ^ + j ^ 2