In a plane electromagnetic wave, E⃗ is along k̂ and B⃗ is along 2î-2ĵ. Find the unit vector in the propagation direction.
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Question

In a plane electromagnetic wave, E⃗ is along k̂ and B⃗ is along 2î−2ĵ. Find the unit vector in the propagation direction.

G1 Physics · Accepted Answer

Propagation is along E⃗×B⃗. Here E⃗∥k̂ and B⃗∥2î−2ĵ. Thus k̂×(2î−2ĵ)=2î+2ĵ, whose unit direction is (î+ĵ)/√2. Option A.