The electric and the magnetic field, associated with an electromagnetic wave, propagating along the…

The electric and the magnetic field, associated with an electromagnetic wave, propagating along the $+z$-axis, can be represented by
  1. $\left[\mathbf{E}=E_0 \hat{\mathbf{k}}, \mathbf{B}=B_0 \hat{\mathbf{i}}\right]$
  2. $\left[\mathbf{E}=E_0 \hat{\mathbf{j}}, \mathbf{B}=B_0 \hat{\mathbf{j}}\right]$
  3. $\left[\mathbf{E}=E_0 \hat{\mathbf{j}}, \mathbf{B}=B_0 \hat{\mathbf{k}}\right]$
  4. $\left[\mathbf{E}=E_0 \hat{\mathbf{i}}, \mathbf{B}=B_0 \hat{\mathbf{j}}\right]$

Solution

$\vec{\mu}=\overrightarrow{\mathbf{E}} \times \overrightarrow{\mathbf{B}}$ $=E_0 \hat{\mathbf{i}}+B_0 \hat{\mathbf{j}}=E_0 B_0 \hat{\mathbf{k}}$ $\overrightarrow{\mathbf{E}} \times \overrightarrow{\mathbf{B}}$ points in the direction of wave propagation.

Asked in: NEET 2011 (Screening)

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