Electromagnetic Waves - Result Question 2
2. An em wave is propagating in a medium with a velocity $\vec{V}=V \hat{i}$. The instantaneous oscillating electric field of this em wave is along $+y$ axis. Then the direction of oscillating magnetic field of the em wave will be along
[2018]
(a) $-z$ direction
(b) $+z$ direction
(c) $-x$ direction
(d) $-y$ direction
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Answer:
Correct Answer: 2. (b)
Solution:
- (b) As we know,
$ \begin{aligned} & \vec{E} \times \vec{B}=\vec{V} \\ & (\hat{E j}) \times(\vec{B})=V \hat{i} \\ & (\because \text{ Electric field vector is along +y axis }) \end{aligned} $
So, $\vec{B}=B \hat{k}$
i.e., direction of magnetic field vector is along $+z$ direction.
