JEE PYQ: Electromagnetic Waves Question 32
Question 32 - 2019 (12 Apr 2019 Shift 1)
An electromagnetic wave is represented by the electric field $\vec{E} = E_0 \hat{n} \sin[\omega t + (6y - 8z)]$. Taking unit vectors in x, y and z directions to be $\hat{i}, \hat{j}, \hat{k}$, the direction of propagation $\hat{s}$ is:
(1) $\hat{s} = \frac{3\hat{i} - 4\hat{j}}{5}$
(2) $\hat{s} = \frac{-4\hat{k} + 3\hat{j}}{5}$
(3) $\hat{s} = \frac{-3\hat{j} + 4\hat{k}}{5}$
(4) $\hat{s} = \frac{3\hat{j} - 3\hat{k}}{5}$
Show Answer
Answer: (3)
Solution
$\hat{s} = \frac{-3\hat{j} + 4\hat{k}}{5}$ (opposite to the spatial part direction since wave has $\sin[\omega t + …]$).
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