Em Waves Question 70
Question: A plane electromagnetic wave $ E _{z}=100\cos (6\times 10^{8}t+4x)V/m $ propagates in a medium of dielectric constant
Options:
A) 1.5
B) 2.0
C) 2.4
D) 4.0
Show Answer
Answer:
Correct Answer: B
Solution:
[b] Comparing the given equation with equation of plane electromagnetic wave, $ E _{z}=E _{0}\cos (\omega t+kx) $ , we have $ \omega =6\times {{10}^{-8}} $ and $ k=4. $ Velocity of light in medium $ v=\frac{\omega }{k}=\frac{6\times 10^{8}}{4}=\frac{3}{2}\times 10^{8}m/s $ Refractive index, $ \mu =\frac{c}{v}=\frac{3\times 10^{8}}{(3/2)\times 10^{8}}=2 $
BETA
