Em Waves Question 92
Question: For plane electromagnetic waves propagating in the z-direction, which one of the following combination gives the correct possible direction for $ \vec{E} $ and $ \vec{B} $ field respectively?
Options:
A) $ (2\hat{i}+3\hat{j}) $ and $ (\hat{i}+2\hat{j}) $
B) $ (-2\hat{i}-3\hat{j}) $ and $ (3\hat{i}-2\hat{j}) $
C) $ (3\hat{i}+4\hat{j}) $ and $ (4\hat{i}-3\hat{j}) $
D) $ (\hat{i}+2\hat{j}) $ and $ (2\hat{i}-\hat{j}) $
Show Answer
Answer:
Correct Answer: B
Solution:
[b] As we know, $ \vec{E}.\vec{B}=0 $
$ \because [\vec{E}\bot \vec{B}] $ and $ \vec{E}\times \vec{B} $ should be along Z direction As $ (-2\hat{i}-3\hat{j})\times (3\hat{i}-2\hat{j})=5\hat{k} $ Hence option is the correct answer.
BETA
