A plane electromagnetic wave is propagating along the direction i+ j √2, with its polarization along the direction k. The correct form of the…
JEE Main 2020 — Physics Electromagnetism
2020mcqmedium
A plane electromagnetic wave is propagating along the direction 2i^+j^, with its polarization along the direction k.^ The correct form of the magnetic field of the wave would be (here B0 is an appropriate constant):
Official previous-year question
Held on 9 Jan 2020 · Verified 6 Jul 2026.
Options
A
B02i^−j^cos(ωt−k2i^+j^)
B
B02j^−i^cos(ωt+k2i^+j^)
C
B0k^cos(ωt−k2i^+j^)
D
B02i^+j^cos(ωt−k2i^+j^)
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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^=2i^+j^ (Given)
B^ denotes unit magnetic field vector.
B^=C^×E^
B^=2i^+j^×k^=2i^−j^
General Form is B=(B0B^)cos(ωt−c^k)
where B0 is Magnitude of Magnetic Field
So,B=B02i^−j^cos(ωt−k2i^+j^)
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