Question

If an EM wave travels in a medium with \(\varepsilon_r = 4\), \(\mu_r = 1\), its speed (in ms\(^{-1}\)) in terms of \(c\) (\(c =\) velocity of light in free space) is}

• A. [option in figure]
• B. [option in figure]
• C. [option in figure]
• D. [option in figure]
• E. [option in figure]

Hint:

Speed of electromagnetic wave in a medium: \[ v=\frac{c}{\sqrt{\mu_r\varepsilon_r}} \]

Answer 1

The Correct Option is C

Speed of EM wave in a medium is: \[ v=\frac{c}{\sqrt{\mu_r\varepsilon_r}} \] Given: \[ \mu_r=1,\qquad \varepsilon_r=4 \] So, \[ v=\frac{c}{\sqrt{1\times 4}}=\frac{c}{2} \]
Hence, the correct answer is the option corresponding to: \[ \boxed{\frac{c}{2}} \]