Question 77: EM waves

Question

An electromagnetic wave is transporting energy in the negative $$z$$ direction. At a certain point and certain time the direction of electric field of the wave is along positive $$y$$ direction. What will be the direction of the magnetic field of the wave at that point and instant?

Accepted Answer

As, poynting vector
$$
\overrightarrow{\mathrm{S}}=\overrightarrow{\mathrm{E}} 	imes \overrightarrow{\mathrm{H}}
$$
Given energy transport $=$ negative $\mathrm{z}$ direction
Electric field $=$ positive $\mathrm{y}$ direction
$(-\hat{\mathrm{k}})=(+\hat{\mathrm{j}}) 	imes[\hat{\mathrm{i}}]$
Hence according to vector cross product magnetic field should be positive $\mathrm{x}$ direction.

Answer

Negative direction of $$y$$

Answer

Positive direction of $$z$$

Answer

Positive direction of $$x$$

Answer

Negative direction $$x$$

EM waves

An electromagnetic wave is transporting energy in the negative $z direction. At a certain point and certain time the direction of electric field of the wave is along positive y$ direction. What will be the direction of the magnetic field of the wave at that point and instant?

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