The electric field of a plane electromagnetic wave is E⃗=E₀(î+ĵ)/√2 cos(kz+ωt). At t=0, a positively charged particle is at (0,0,π/k). If its instantaneous velocity is v₀k̂, the force on it due to the wave is:
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Question

The electric field of a plane electromagnetic wave is E⃗=E₀(î+ĵ)/√2 cos(kz+ωt). At t=0, a positively charged particle is at (0,0,π/k). If its instantaneous velocity is v₀k̂, the force on it due to the wave is:

Options

G1 Physics · Accepted Answer

At z=π/k and t=0, the cosine factor is −1. Using the EM-wave relation between E⃗ and B⃗ and the given particle velocity, q(E⃗+v⃗×B⃗) is directed antiparallel to (î+ĵ)/√2. Option C.