The electric field in an electromagnetic wave is given by $\vec{E}$ = 40 cos[ω(t - z/c)] î N C⁻¹. The magnetic field induction of this wave is (in SI unit):
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The electric field in an electromagnetic wave is given by E ⃗ \vec{E} E = 40 cos[ω(t - z/c)] î N C⁻¹. The magnetic field induction of this wave is (in SI unit):

G1 Physics · Accepted Answer

Given: E⃗ = 40 cos[ω(t - z/c)] î The electric field is along +x direction and the wave propagates along +z direction. For an electromagnetic wave: E⃗ × B⃗ gives the direction of propagation. Since: î × ĵ = k̂ B⃗ must be along +y direction. Also, B = E/c Therefore, B⃗ = (40/c) cos[ω(t - z/c)] ĵ