QJEEM19Ph54ee: JEE Main 2019 Physics - Class 12 JEEM19Ph54ee Solution: An electromagnetic wave is represented by the electric field E…

Question

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An electromagnetic wave is represented by the electric field

\vec{E} = E_{0} \hat{n} \sin [ω t + (6 y - 8 z)]

. Taking unit vectors in x, y and z directions to be

\hat{i}, \hat{j}, \hat{k}

, the direction of propagation

\hat{s}

, is :

Accepted Answer

\vec{E} = E_{0} \hat{n} \sin (ω t + (6 y - 8 z))

= E_{0} \hat{n} \sin (ω t + \vec{k} . \vec{r})

where

\vec{r} = x \hat{i} + y \hat{j} + z \hat{k}

and

\vec{k} . \vec{r} = 6 y - 8 z

\Rightarrow \vec{k} = 6 \hat{j} - 8 \hat{k}

direction of propagation

\hat{s} = - \hat{k} = (\frac{- 3 \hat{j} + 4 \hat{k}}{5})

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