Em Waves Question 111
Question: A plane electromagnetic wave travels in free space along X-direction. If the value of $ \vec{B} $ (in tesla) at a particular point in space and time is $ 1.2\times {{10}^{-8}}\hat{k} $ . The value of $ \vec{E} $ (in $ V{{m}^{-1}} $ ) at that point is
Options:
A) $ 1.,2\hat{j} $
B) $ 3.,6,\hat{k} $
C) $ 1.,2,\hat{k} $
D) $ 3.,6\hat{j} $
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Answer:
Correct Answer: D
Solution:
[d] Given: $ \vec{B}=1.2\times {{10}^{-8}}\hat{k}T $
$ \vec{E}=? $ From formula, B is along Z-direction and the $ E=Bc=(1.2\times {{10}^{-8}}T)(3\times 10^{8},m{{s}^{-1}})=3.6V{{m}^{-1}} $
$ \vec{B} $ is along Z-direction and the wave propagates along X-direction.
Therefore $ \vec{E} $ should be along Y-direction. Thus, $ \vec{E}=3.6\hat{j},V{{m}^{-1}} $
BETA
