Choose the best answer:
1. The absolute refractive index of Ruby is \(1.7\). Find the speed of light in Ruby. The speed of light in vacuum is \(3\ \times\ 10^8\ \frac{m}{s}\).
2. The speed of light in glass is \(2\ \times\ 10^8\ \frac{m}{s}\) and in water is \(2.25\ \times\ 10^8\ \frac{m}{s}\). Which one of the two is optically denser.