The speed of light in vacuum is $3\times 10^8 m/s$. The refractive index of material x is 1.8. The speed of light in material x would be
Answer & explanation
Correct answer: option 2
$\text{The speed of light in material x is }v = \frac{c}{\mu} = \frac{3\times 10^8}{1.8} = 1.67\times 10^8m/s$